A Tour of The Summa

Recommended reading:

A Tour of The Summa: A Journey Through St. Thomas Aquinas' Summa Theologica, by Rt. Rev. Msgr. Paul J. Glenn 

"This unique synopsis of the Summa Theologica is a complete, chapter-by-chapter restatement of St. Thomas' work, intended to expose readers to the totality of St. Thomas' thought and yet be brief enough to fit into one volume. Author of eleven other books on philosophy, Msgr. Glenn brings to this work—by far his greatest—a lifetime of teaching and writing experience. A masterpiece in its own right."—TAN Books

"The Summa Theologica is considered by the Catholic Church to be the most important of the many works which the towering  St. Thomas Aquinas enriched the world. But many lack the inclination or opportunity to spend years of sustained effort to study it.

"A TOUR OF THE SUMMA was written especially for those persons. It is a journey through the greatest work of a Doctor of the Church, rendering St. Thomas' arguments in a shortened yet rigorously faithful form.

"Msgr. Paul J. Glenn brings a lifetime of teaching and writing experience to this, his masterwork. Here he distills the core of the Angelic Doctor's treatise into a dense yet highly readable single volume that makes the Summa accessible to all.

"A TOUR OF THE SUMMA will serve as both a road map and masterkey, unlocking the rich landscape of St. Thomas' insights and glorious mind."

—From the back cover.

■ See this book: at Amazon, or, at TAN Books

On good government

"IF, therefore, a multitude of free men is ordered by the ruler towards the common good of the multitude, that rulership will be right and just, as is suitable to free men. If, on the other hand, a rulership aims, not at the common good of the multitude, but at the private good of the ruler, it will be an unjust and perverted rulership. The Lord, therefore, threatens such rulers, saying by the mouth of Ezekiel: “Woe to the shepherds that feed themselves (seeking, that is, their own interest): should not the flocks be fed by the shepherd?” Shepherds indeed should seek the good of their flocks, and every ruler, the good of the multitude subject to him."

~St. Thomas Aquinas: De Regno (On Kingship to the King of Cyprus), Bk. 1, Chap. 2.

On Kingship to the King of Cyprus
 Pontifical Institute of Mediaeval Studies; Revised edition (January 1, 1949)

■ See this book at Amazon

Effects of Good Government on the City Life (detail).
By Ambrogio Lorenzetti. Fresco, 1338-40; Palazzo Pubblico, Siena.

On the Hail Mary

THE ANGELIC SALUTATION

A Commentary by St. Thomas Aquinas

THIS salutation has three parts. The Angel gave one part, namely: “Hail, full of grace, the Lord is with you, blessed art you among women” (Lk 1:28). The other part was given by Elizabeth, the mother of John the Baptist, namely: “Blessed is the fruit of your womb” (Lk 1:42). The Church adds the third part, that is, “Mary,” because the Angel did not say, “Hail, Mary,” but “Hail, full of grace.” But, as we shall see, this name, “Mary,” according to its meaning agrees with the words of the Angels. [The Hail Mary or Angelical Salutation or Ave Maria in the time of St. Thomas consisted only of the present first part of the prayer. The second part—“Holy Mary, Mother of God,” etc.—was also added by the Church later.].

“Hail Mary”

We must now consider concerning the first part of this prayer that in ancient times it was no small event when Angels appeared to men; and that man should show them reverence was especially praiseworthy. Thus, it is written to the praise of Abraham that he received the Angels with all courtesy and showed them reverence. But that an Angel should show reverence to a man was never heard of until the Angel reverently greeted the Blessed Virgin saying: “Hail.”

In olden time an Angel would not show reverence to a man, but a man would deeply revere an Angel. This is because Angels are greater than men, and indeed in three ways. First, they are greater than men in dignity. This is because the Angel is of a spiritual nature: “You make your angels spirits” (Ps 103:4). But, on the other hand, man is of a corruptible nature, for Abraham said: “I will speak to my Lord, whereas I am dust and ashes” (Gen 18:27). It was not fitting, therefore, that a spiritual and incorruptible creature should show reverence to one that is corruptible as is a man. Secondly, an Angel is closer to God. The Angel, indeed, is of the family of God, and as it were stands ever by Him: “Thousands of thousands ministered to Him, and ten thousand times a hundred thousand stood before Him” (Dan 7:10). Man, on the other hand, is rather a stranger and afar off from God because of sin: “I have gone afar off” (Ps 44:8). Therefore, it is fitting that man should reverence an Angel who is an intimate and one of the household of the King.

Then, thirdly, the Angels far exceed men in the fullness of the splendor of divine grace. For Angels participate in the highest degree in the divine light: “Is there any numbering of His soldiers? And upon whom shall not His light arise?”(Job 25:3). Hence, the Angels always appear among men clothed in light, hut men on the contrary, although they partake somewhat of the light of grace, nevertheless do so in a much slighter degree and with a certain obscurity. It was, therefore, not fitting that an Angel should show reverence to a man until it should come to pass that one would be found in human nature who exceeded the Angels in these three points in which we have seen that they excel over men—and this was the Blessed Virgin. To show that she excelled the Angels in these, the Angel desired to show her reverence, and so he said: “Ave (Hail).”

“Full of grace”

The Blessed Virgin was superior to any of the Angels in the fullness of grace, and as an indication of this the Angel showed reverence to her by saying: “Full of grace.” This is as if he said: “I show you reverence because you dost excel me in the fullness of grace.”

The Blessed Virgin is said to be full of grace in three ways. First, as regards her soul she was full of grace. The grace of God is given for two chief purposes, namely, to do good and to avoid evil. The Blessed Virgin, then, received grace in the most perfect degree, because she had avoided every sin more than any other Saint after Christ. Thus it is said: “You are fair, My beloved, and there is not a spot in you” (Sg 4:7). St. Augustine says: “If we could bring together all the Saints and ask them if they were entirely without sin, all of them, with the exception of the Blessed Virgin, would say with one voice: ‘If we say that we have no sin, we deceive ourselves and the truth is not in us.’ (1 Jn 1:8). I except, however, this holy Virgin of whom, because of the honor of God, I wish to omit all mention of sin” (De natura et gratia 36). For we know that to her was granted grace to overcome every kind of sin by Him whom she merited to conceive and bring forth, and He certainly was wholly without sin.

Christ excelled the Blessed Virgin in this, that He was conceived and born without original sin, while the Blessed Virgin was conceived in original sin, but was not born in it. [as in Summa, but otherwise in I Sent., c. 44, q. 1, ad. 3]. She exercised the works of all the virtues, whereas the Saints are conspicuous for the exercise of certain special virtues. Thus, one excelled in humility, another in chastity, another in mercy, to the extent that they are the special exemplars of these virtues—as, for example, St. Nicholas is an exemplar of the virtue of mercy. The Blessed Virgin is the exemplar of all the virtues.

In her is the fullness of the virtue of humility: “Behold the handmaid of the Lord” (Lk 1:38). And again: “He has looked on the humility of his handmaid” (Lk 1:48). So she is also exemplar of the virtue of chastity: “Because I know not man” (Lk 1:34). And thus it is with all the virtues, as is evident. Mary was full of grace not only in the performance of all good, but also in the avoidance of all evil. Again, the Blessed Virgin was full of grace in the overflowing effect of this grace upon her flesh or body. For while it is a great thing in the Saints that the abundance of grace sanctified their souls, yet, moreover, the soul of the holy Virgin was so filled with grace that from her soul grace poured into her flesh from which was conceived the Son of God. Hugh of St. Victor says of this: “Because the love of the Holy Spirit so inflamed her soul, He worked a wonder in her flesh, in that from it was born God made Man.” “And therefore also the Holy which shall be born of you shall be called the Son of God” (Lk 1:35).

The plenitude of grace in Mary was such that its effects overflow upon all men. It is a great thing in a Saint when he has grace to bring about the salvation of many, but it is exceedingly wonderful when grace is of such abundance as to be sufficient for the salvation of all men in the world, and this is true of Christ and of the Blessed Virgin. Thus, “a thousand bucklers,” that is, remedies against dangers, “hang therefrom” (Sg 4:4). Likewise, in every work of virtue one can have her as one’s helper. Of her it was spoken: “In me is all grace of the way and of the truth, in me is all hope of life and of virtue” (Sir 24:25). Therefore, Mary is full of grace, exceeding the Angels in this fullness and very fittingly is she called “Mary” which means “in herself enlightened”: “The Lord will fill your soul with brightness” (Is 48:11). And she will illumine others throughout the world for which reason she is compared to the sun and to the moon.

“The Lord is with you”

The Blessed Virgin excels the Angels in her closeness to God. The Angel Gabriel indicated this when he said: “The Lord is with you”—as if to say: “I reverence you because you art nearer to God than I, because the Lord is with you.” By the Lord; he means the Father with the Son and the Holy Spirit, who in like manner are not with any Angel or any other spirit: “The Holy which shall be born of you shall be called the Son of God” (Lk 1:35). God the Son was in her womb: “Rejoice and praise, O you habitation of Sion; for great is He that is in the midst of you, the Holy One of Israel” (Is 12:6).

The Lord is not with the Angel in the same manner as with the Blessed Virgin; for with her He is as a Son, and with the Angel He is the Lord. The Lord, the Holy Ghost, is in her as in a temple, so that it is said: “The temple of the Lord, the sanctuary of the Holy Spirit,” (Benedictus antiphon from the Little Office of Blessed Virgin), because she conceived by the Holy Ghost. “The Holy Ghost shall come upon you” (Lk 1:35). The Blessed Virgin is closer to God than is an Angel, because with her are the Lord the Father, the Lord the Son, and the Lord the Holy Ghost—in a word, the Holy Trinity. Indeed of her we sing: “Noble resting place of the Triune God.” “The Lord is with you” are the most praiseladen words that the Angel could have uttered; and, hence, he so profoundly reverenced the Blessed Virgin because she is the Mother of the Lord and Our Lady. Accordingly she is very well named “Mary,” which in the Syrian tongue means “Lady.”

“Blessed art you among women”

The Blessed Virgin exceeds the Angels in purity. She is not only pure, but she obtains purity for others. She is purity itself, wholly lacking in every guilt of sin, for she never incurred either mortal or venial sin. So, too, she was free from the penalties of sin. Sinful man, on the contrary, incurs a threefold curse on account of sin. The first fell upon woman who conceives in corruption, bears her child with difficulty, and brings it forth in pain. The Blessed Virgin was wholly free from this, since she conceived without corruption, bore her Child in comfort, and brought Him forth in joy: “It shall bud forth and blossom, and shall rejoice with joy and praise” (Is 35:2).

The second penalty was inflicted upon man in that he shall earn his bread by the sweat of his brow. The Blessed Virgin was also immune from this because, as the Apostle says, virgins are free from the cares of this world and are occupied wholly with the things of the Lord (1 Cor 7:34).

The third curse is common both to man and woman in that both shall one day return to dust. The Blessed Virgin was spared this penalty, for her body was raised up into heaven, and so we believe that after her death she was revived and transported into heaven: “Arise, O Lord, into your resting place, You and the ark which You hast sanctified” (Ps 131:8). Because the Blessed Virgin was immune from these punishments, she is “blessed among women.” Moreover, she alone escaped the curse of sin, brought forth the Source of blessing, and opened the gate of heaven. It is surely fitting that her name is “Mary,” which is akin to the Star of the Sea (“Maria—maris stella”), for just as sailors are directed to port by the star of the sea, so also Christians are by Mary guided to glory.

“Blessed is the fruit of your womb”

The sinner often seeks for something which he does not find; but to the just man it is given to find what he seeks: “The substance of the sinner is kept for the just” (Prov 13:22). Thus, Eve sought the fruit of the tree (of good and evil), but she did not find in it that which she sought. Everything Eve desired, however, was given to the Blessed Virgin. Eve sought that which the devil falsely promised her, namely, that she and Adam would be as gods, knowing good and evil. “You shall be,” says this liar, “as gods” (Gen 3:5). But he lied, because “he is a liar and the father of lies” (Jn 8:44). Eve was not made like God after having eaten of the fruit, but rather she was unlike God in that by her sin she withdrew from God and was driven out of paradise. The Blessed Virgin, however, and all Christians found in the Fruit of her womb Him whereby we are all united to God and are made like to Him: “When He shall appear, we shall be like to Him, because we shall see Him as He is” (1 Jn 3:2).

Eve looked for pleasure in the fruit of the tree because it was good to eat. But she did not find this pleasure in it, and, on the contrary, she at once discovered she was naked and was stricken with sorrow. In the Fruit of the Blessed Virgin we find sweetness and salvation: “He who eats My flesh... has eternal life” (Jn 6:55).

The fruit which Eve desired was beautiful to look upon, but that Fruit of the Blessed Virgin is far more beautiful, for the Angels desire to look upon Him: “You are beautiful above the sons of men” (Ps 44:3). He is the splendor of the glory of the Father. Eve, therefore, looked in vain for that which she sought in the fruit of the tree, just as the sinner is disappointed in his sins. We must seek in the Fruit of the womb of the Virgin Mary whatsoever we desire. This is He who is the Fruit blessed by God, who has filled Him with every grace, which in turn is poured out upon us who adore Him: “Blessed be God and the Father of our Lord Jesus Christ, who has blessed us with spiritual blessings in Christ” (Eph 1:3). He, too, is revered by the Angels: “Benediction and glory and wisdom and thanksgiving, honor and power and strength, to our God” (Rev 7:12). And He is glorified by men: “Every tongue should confess that the Lord Jesus Christ is in the glory of God the Father” (Phil 2:11). The Blessed Virgin is indeed blessed, but far more blessed is the Fruit of her womb: “Blessed is He who comes in the name of the Lord” (Ps 117:26).

+ + +

Translated by Joseph B. Collins, New York, 1939.

The Annunciation, by Fra Angelico.

Tempera on wood, 1430-32; Museo del Prado, Madrid.

The Aquinas Prayer Book

O MOST blessed and sweet Virgin Mary,
Mother of God, filled with all tenderness,
Daughter of the most high King, 
Lady of the Angels,
Mother of all the faithful,

On this day and all the days of my life,
I entrust to your merciful heart my body and my soul,
all my acts, thoughts, choices,
desires, words, deeds,
my entire life and death,

So that, with your assistance,
all may be ordered to the good
according to the will of your beloved Son, our Lord Jesus Christ. . . .

From your beloved Son. . . .
request for me the grace to resist firmly
the temptations of the world, the flesh and the devil. . . .

My most holy Lady,
I also beseech you to obtain for me 
true obedience and true humility of heart

So that I may recognize myself truly
as a sinner─wretched and weak─ 
and powerless, 
without the grace and help of my Creator
and without your holy prayers. . . .

Obtain for me as well,
O most sweet Lady,
true charity with which from the depths of my heart 
I may love your most holy Son, our Lord Jesus Christ,
and, after Him,
love you above all other things. . . .

Grant, O Queen of Heaven,
that ever in my heart 
I may have fear and love alike 
for your most sweet Son. . . .

I pray also that, at the end of my life,
you,
Mother without compare,
Gate of Heaven and Advocate of sinners. . . .
will protect me with your great piety and mercy. . . .

and obtain for me, through the blessed and glorious Passion of your Son
and through your own intercession, 
received in hope, the forgiveness of all my sins.

When I die in your love and His love,
may you direct me
into the way of salvation and blessedness.
Amen.

─Brief excerpts from "Prayer of St. Thomas Aquinas to the Blessed Virgin" (Devoutly I Adore Thee).

The Aquinas Prayer Book:
The Prayers and Hymns of St. Thomas Aquinas

■ At Amazon

■ At Sophia Institute Press

On Lust

Summa Theologica
Second Part of the Second Part (Secunda Secundae Partis)
Question 154. The parts of Lust

1. Into what parts is lust divided?
2. Is simple fornication a mortal sin?
3. Is it the greatest of sins?
4. Is there mortal sin in touches, kisses and such like seduction?
5. Is nocturnal pollution a mortal sin?
6. Seduction
7. Rape
8. Adultery
9. Incest
10. Sacrilege
11. The sin against nature
12. The order of gravity in the aforesaid sins


Article 1. Whether six species are fittingly assigned to lust?

_______________________________________

Objection 1. It would seem that six species are unfittingly assigned to lust, namely, "simple fornication, adultery, incest, seduction, rape, and the unnatural vice." For diversity of matter does not diversify the species. Now the aforesaid division is made with regard to diversity of matter, according as the woman with whom a man has intercourse is married or a virgin, or of some other condition. Therefore it seems that the species of lust are diversified in this way.

Objection 2. Further, seemingly the species of one vice are not differentiated by things that belong to another vice. Now adultery does not differ from simple fornication, save in the point of a man having intercourse with one who is another's, so that he commits an injustice. Therefore it seems that adultery should not be reckoned a species of lust.

Objection 3. Further, just as a man may happen to have intercourse with a woman who is bound to another man by marriage, so may it happen that a man has intercourse with a woman who is bound to God by vow. Therefore sacrilege should be reckoned a species of lust, even as adultery is.

Objection 4. Further, a married man sins not only if he be with another woman, but also if he use his own wife inordinately. But the latter sin is comprised under lust. Therefore it should be reckoned among the species thereof.

Objection 5. Further, the Apostle says (2 Cor 12:21): "Lest again, when I come, God humble me among you, and I mourn many of them that sinned before, and have not done penance for the uncleanness and fornication and lasciviousness that they have committed." Therefore it seems that also uncleanness and lasciviousness should be reckoned species of lust, as well as fornication.

Objection 6. Further, the thing divided is not to be reckoned among its parts. But lust is reckoned together with the aforesaid: for it is written (Gal 5:19): "The works of the flesh are manifest, which are fornication, uncleanness, immodesty, lust [Douay: 'luxury']." Therefore it seems that fornication is unfittingly reckoned a species of lust.

On the contrary, The aforesaid division is given in the Decretals 36, qu. i [Append. Grat. ad can. Lex illa].

I answer that, As stated above (Q. 153, A. 3), the sin of lust consists in seeking venereal pleasure not in accordance with right reason. This may happen in two ways. First, in respect of the matter wherein this pleasure is sought; secondly, when, whereas there is due matter, other due circumstances are not observed. And since a circumstance, as such, does not specify a moral act, whose species is derived from its object which is also its matter, it follows that the species of lust must be assigned with respect to its matter or object.

Now this same matter may be discordant with right reason in two ways. First, because it is inconsistent with the end of the venereal act. On this way, as hindering the begetting of children, there is the "vice against nature," which attaches to every venereal act from which generation cannot follow; and, as hindering the due upbringing and advancement of the child when born, there is "simple fornication," which is the union of an unmarried man with an unmarried woman. Secondly, the matter wherein the venereal act is consummated may be discordant with right reason in relation to other persons; and this in two ways. First, with regard to the woman, with whom a man has connection, by reason of due honor not being paid to her; and thus there is "incest," which consists in the misuse of a woman who is related by consanguinity or affinity. Secondly, with regard to the person under whose authority the woman is placed: and if she be under the authority of a husband, it is "adultery," if under the authority of her father, it is "seduction," in the absence of violence, and "rape" if violence be employed.

These species are differentiated on the part of the woman rather than of the man, because in the venereal act the woman is passive and is by way of matter, whereas the man is by way of agent; and it has been stated above (Obj. 1) that the aforesaid species are assigned with regard to a difference of matter.

Reply to Objection 1. The aforesaid diversity of matter is connected with a formal difference of object, which difference results from different modes of opposition to right reason, as stated above.

Reply to Objection 2. As stated above (I-II, 18, 07), nothing hinders the deformities of different vices concurring in the one act, and in this way adultery is comprised under lust and injustice. Nor is this deformity of injustice altogether accidental to lust: since the lust that obeys concupiscence so far as to lead to injustice, is thereby shown to be more grievous.

Reply to Objection 3. Since a woman, by vowing continence, contracts a spiritual marriage with God, the sacrilege that is committed in the violation of such a woman is a spiritual adultery. On like manner, the other kinds of sacrilege pertaining to lustful matter are reduced to other species of lust.

Reply to Objection 4. The sin of a husband with his wife is not connected with undue matter, but with other circumstances, which do not constitute the species of a moral act, as stated above (I-II, 18, 2).

Reply to Objection 5. As a gloss says on this passage, "uncleanness" stands for lust against nature, while "lasciviousness" is a man's abuse of boys, wherefore it would appear to pertain to seduction. We may also reply that "lasciviousness" relates to certain acts circumstantial to the venereal act, for instance kisses, touches, and so forth.

Reply to Objection 6. According to a gloss on this passage "lust" there signifies any kind of excess.

Article 2. Whether simple fornication is a mortal sin?

_______________________________________

Objection 1. It would seem that simple fornication is not a mortal sin. For things that come under the same head would seem to be on a par with one another. Now fornication comes under the same head as things that are not mortal sins: for it is written (Acts 15:29): "That you abstain from things sacrificed to idols, and from blood, and from things strangled, and from fornication." But there is not mortal sin in these observances, according to (1 Tim 4:4), "Nothing is rejected that is received with thanksgiving." Therefore fornication is not a mortal sin.

Objection 2. Further, no mortal sin is the matter of a Divine precept. But the Lord commanded (Hos 1:2): "Go take thee a wife of fornications, and have of her children of fornications." Therefore fornication is not a mortal sin.

Objection 3. Further, no mortal sin is mentioned in Holy Writ without disapprobation. Yet simple fornication is mentioned without disapprobation by Holy Writ in connection with the patriarchs. Thus we read (Gen 16:4) that Abraham went in to his handmaid Agar; and further on (Gen 30:5-9) that Jacob went in to Bala and Zelpha the handmaids of his wives; and again (Gen 38:18) that Juda was with Thamar whom he thought to be a harlot. Therefore simple fornication is not a mortal sin.

Objection 4. Further, every mortal sin is contrary to charity. But simple fornication is not contrary to charity, neither as regards the love of God, since it is not a sin directly against. God, nor as regards the love of our neighbor, since thereby no one is injured. Therefore simple fornication is not a mortal sin.

Objection 5. Further, every mortal sin leads to eternal perdition. But simple fornication has not this result: because a gloss of Ambrose [The quotation is from the Gloss of Peter Lombard, who refers it to St. Ambrose: whereas it is from Hilary the deacon] on (1 Tim 4:8), "Godliness is profitable to all things," says: "The whole of Christian teaching is summed up in mercy and godliness: if a man conforms to this, even though he gives way to the inconstancy of the flesh, doubtless he will be punished, but he will not perish." Therefore simple fornication is not a mortal sin.

Objection 6. Further, Augustine says (De Bono Conjug. xvi) that "what food is to the well-being of the body, such is sexual intercourse to the welfare of the human race." But inordinate use of food is not always a mortal sin. Therefore neither is all inordinate sexual intercourse; and this would seem to apply especially to simple fornication, which is the least grievous of the aforesaid species.

On the contrary, It is written (Tob 4:13): "Take heed to keep thyself . . . from all fornication, and beside thy wife never endure to know a crime." Now crime denotes a mortal sin. Therefore fornication and all intercourse with other than one's wife is a mortal sin.

Further, nothing but mortal sin debars a man from God's kingdom. But fornication debars him, as shown by the words of the Apostle (Gal 5:21), who after mentioning fornication and certain other vices, adds: "They who do such things shall not obtain the kingdom of God." Therefore simple fornication is a mortal sin.

Further, it is written in the Decretals (XXII, qu. i, can. Praedicandum): "They should know that the same penance is to be enjoined for perjury as for adultery, fornication, and wilful murder and other criminal offenses." Therefore simple fornication is a criminal or mortal sin.

I answer that, Without any doubt we must hold simple fornication to be a mortal sin, notwithstanding that a gloss [St. Augustine, QQ. in Deut., qu. 37 on Deuteronomy 23:17, says: "This is a prohibition against going with whores, whose vileness is venial." For instead of "venial" it should be "venal," since such is the wanton's trade. On order to make this evident, we must take note that every sin committed directly against human life is a mortal sin. Now simple fornication implies an inordinateness that tends to injure the life of the offspring to be born of this union. For we find in all animals where the upbringing of the offspring needs care of both male and female, that these come together not indeterminately, but the male with a certain female, whether one or several; such is the case with all birds: while, on the other hand, among those animals, where the female alone suffices for the offspring's upbringing, the union is indeterminate, as in the case of dogs and like animals. Now it is evident that the upbringing of a human child requires not only the mother's care for his nourishment, but much more the care of his father as guide and guardian, and under whom he progresses in goods both internal and external. Hence human nature rebels against an indeterminate union of the sexes and demands that a man should be united to a determinate woman and should abide with her a long time or even for a whole lifetime. Hence it is that in the human race the male has a natural solicitude for the certainty of offspring, because on him devolves the upbringing of the child: and this certainly would cease if the union of sexes were indeterminate.

This union with a certain definite woman is called matrimony; which for the above reason is said to belong to the natural law. Since, however, the union of the sexes is directed to the common good of the whole human race, and common goods depend on the law for their determination, as stated above (I-II, 90, 2), it follows that this union of man and woman, which is called matrimony, is determined by some law. What this determination is for us will be stated in the Third Part of this work (Supplement, 050, seqq.), where we shall treat of the sacrament of matrimony. Wherefore, since fornication is an indeterminate union of the sexes, as something incompatible with matrimony, it is opposed to the good of the child's upbringing, and consequently it is a mortal sin.

Nor does it matter if a man having knowledge of a woman by fornication, make sufficient provision for the upbringing of the child: because a matter that comes under the determination of the law is judged according to what happens in general, and not according to what may happen in a particular case.

Reply to Objection 1. Fornication is reckoned in conjunction with these things, not as being on a par with them in sinfulness, but because the matters mentioned there were equally liable to cause dispute between Jews and Gentiles, and thus prevent them from agreeing unanimously. For among the Gentiles, fornication was not deemed unlawful, on account of the corruption of natural reason: whereas the Jews, taught by the Divine law, considered it to be unlawful. The other things mentioned were loathsome to the Jews through custom introduced by the law into their daily life. Hence the Apostles forbade these things to the Gentiles, not as though they were unlawful in themselves, but because they were loathsome to the Jews, as stated above (I-II, 103, 4, ad 3).

Reply to Objection 2. Fornication is said to be a sin, because it is contrary to right reason. Now man's reason is right, in so far as it is ruled by the Divine Will, the first and supreme rule. Wherefore that which a man does by God's will and in obedience to His command, is not contrary to right reason, though it may seem contrary to the general order of reason: even so, that which is done miraculously by the Divine power is not contrary to nature, though it be contrary to the usual course of nature. Therefore just as Abraham did not sin in being willing to slay his innocent son, because he obeyed God, although considered in itself it was contrary to right human reason in general, so, too, Osee sinned not in committing fornication by God's command. Nor should such a copulation be strictly called fornication, though it be so called in reference to the general course of things. Hence Augustine says (Confess. iii, 8): "When God commands a thing to be done against the customs or agreement of any people, though it were never done by them heretofore, it is to be done"; and afterwards he adds: "For as among the powers of human society, the greater authority is obeyed in preference to the lesser, so must God in preference to all."

Reply to Objection 3. Abraham and Jacob went in to their handmaidens with no purpose of fornication, as we shall show further on when we treat of matrimony (Supplement, 065, 5, ad 2). As to Juda there is no need to excuse him, for he also caused Joseph to be sold.

Reply to Objection 4. Simple fornication is contrary to the love of our neighbor, because it is opposed to the good of the child to be born, as we have shown, since it is an act of generation accomplished in a manner disadvantageous to the future child.

Reply to Objection 5. A person, who, while given to works of piety, yields to the inconstancy of the flesh, is freed from eternal loss, in so far as these works dispose him to receive the grace to repent, and because by such works he makes satisfaction for his past inconstancy; but not so as to be freed by pious works, if he persist in carnal inconstancy impenitent until death.

Reply to Objection 6. One copulation may result in the begetting of a man, wherefore inordinate copulation, which hinders the good of the future child, is a mortal sin as to the very genus of the act, and not only as to the inordinateness of concupiscence. On the other hand, one meal does not hinder the good of a man's whole life, wherefore the act of gluttony is not a mortal sin by reason of its genus. It would, however, be a mortal sin, if a man were knowingly to partake of a food which would alter the whole condition of his life, as was the case with Adam.

Nor is it true that fornication is the least of the sins comprised under lust, for the marriage act that is done out of sensuous pleasure is a lesser sin.

Article 3. Whether fornication is the most grievous of sins?

_______________________________________

Objection 1. It would seem that fornication is the most grievous of sins. For seemingly a sin is the more grievous according as it proceeds from a greater sensuous pleasure. Now the greatest sensuous pleasure is in fornication, for a gloss on (1 Cor 7:9) says that the "flame of sensuous pleasure is most fierce in lust." Therefore it seems that fornication is the gravest of sins.

Objection 2. Further, a sin is the more grievous that is committed against a person more closely united to the sinner: thus he sins more grievously who strikes his father than one who strikes a stranger. Now according to (1 Cor 6:18), "He that committeth fornication sinneth against his own body," which is most intimately connected with a man. Therefore it seems that fornication is the most grievous of sins.

Objection 3. Further, the greater a good is, the graver would seem to be the sin committed against it. Now the sin of fornication is seemingly opposed to the good of the whole human race, as appears from what was said in the foregoing Article. It is also against Christ, according to 1 Corinthians 6:15, "Shall I . . . take the members of Christ, and make them the members of a harlot?" Therefore fornication is the most grievous of sins.

On the contrary, Gregory says (Moral. xxxiii, 12) that the sins of the flesh are less grievous than spiritual sins.

I answer that, The gravity of a sin may be measured in two ways, first with regard to the sin in itself, secondly with regard to some accident. The gravity of a sin is measured with regard to the sin itself, by reason of its species, which is determined according to the good to which that sin is opposed. Now fornication is contrary to the good of the child to be born. Wherefore it is a graver sin, as to its species, than those sins which are contrary to external goods, such as theft and the like; while it is less grievous than those which are directly against God, and sins that are injurious to the life of one already born, such as murder.

Reply to Objection 1. The sensual pleasure that aggravates a sin is that which is in the inclination of the will. But the sensual pleasure that is in the sensitive appetite, lessens sin, because a sin is the less grievous according as it is committed under the impulse of a greater passion. It is in this way that the greatest sensual pleasure is in fornication. Hence Augustine says (De Agone Christiano [Serm. ccxciii; ccl de Temp.; see Appendix to St. Augustine's works]) that of all a Christian's conflicts, the most difficult combats are those of chastity; wherein the fight is a daily one, but victory rare: and Isidore declares (De Summo Bono ii, 39) that "mankind is subjected to the devil by carnal lust more than by anything else," because, to wit, the vehemence of this passion is more difficult to overcome.

Reply to Objection 2. The fornicator is said to sin against his own body, not merely because the pleasure of fornication is consummated in the flesh, which is also the case in gluttony, but also because he acts against the good of his own body by an undue resolution and defilement thereof, and an undue association with another. Nor does it follow from this that fornication is the most grievous sin, because in man reason is of greater value than the body, wherefore if there be a sin more opposed to reason, it will be more grievous.

Reply to Objection 3. The sin of fornication is contrary to the good of the human race, in so far as it is prejudicial to the individual begetting of the one man that may be born. Now one who is already an actual member of the human species attains to the perfection of the species more than one who is a man potentially, and from this point of view murder is a more grievous sin than fornication and every kind of lust, through being more opposed to the good of the human species. Again, a Divine good is greater than the good of the human race: and therefore those sins also that are against God are more grievous. Moreover, fornication is a sin against God, not directly as though the fornicator intended to offend God, but consequently, in the same way as all mortal sins. And just as the members of our body are Christ's members, so too, our spirit is one with Christ, according to 1 Corinthians 6:17, "He who is joined to the Lord is one spirit." Wherefore also spiritual sins are more against Christ than fornication is.

Article 4. Whether there can be mortal sin in touches and kisses?

_______________________________________

Objection 1. It would seem that there is no mortal sin in touches and kisses. For the Apostle says (Eph 5:3): "Fornication and all uncleanness, or covetousness, let it not so much as be named among you, as becometh saints," then he adds: "Or obscenity" (which a gloss refers to "kissing and fondling"), "or foolish talking" (as "soft speeches"), "or scurrility" (which "fools call geniality—i.e. jocularity"), and afterwards he continues (Eph 5:5): "For know ye this and understand that no fornicator, or unclean, or covetous person (which is the serving of idols), hath inheritance in the kingdom of Christ and of God," thus making no further mention of obscenity, as neither of foolish talking or scurrility. Therefore these are not mortal sins.

Objection 2. Further, fornication is stated to be a mortal sin as being prejudicial to the good of the future child's begetting and upbringing. But these are not affected by kisses and touches or blandishments. Therefore there is no mortal sin in these.

Objection 3. Further, things that are mortal sins in themselves can never be good actions. Yet kisses, touches, and the like can be done sometimes without sin. Therefore they are not mortal sins in themselves.

On the contrary, A lustful look is less than a touch, a caress or a kiss. But according to Matthew 5:28, "Whosoever shall look on a woman to lust after her hath already committed adultery with her in his heart." Much more therefore are lustful kisses and other like things mortal sins. Further, Cyprian says (Ad Pompon, de Virgin., Ep. lxii), "By their very intercourse, their blandishments, their converse, their embraces, those who are associated in a sleep that knows neither honor nor shame, acknowledge their disgrace and crime." Therefore by doing these things a man is guilty of a crime, that is, of mortal sin.

I answer that, A thing is said to be a mortal works. sin in two ways. First, by reason of its species, and in this way a kiss, caress, or touch does not, of its very nature, imply a mortal sin, for it is possible to do such things without lustful pleasure, either as being the custom of one's country, or on account of some obligation or reasonable cause. Secondly, a thing is said to be a mortal sin by reason of its cause: thus he who gives an alms, in order to lead someone into heresy, sins mortally on account of his corrupt intention. Now it has been stated above (I-II, 74, 8), that it is a mortal sin not only to consent to the act, but also to the delectation of a mortal sin. Wherefore since fornication is a mortal sin, and much more so the other kinds of lust, it follows that in such like sins not only consent to the act but also consent to the pleasure is a mortal sin. Consequently, when these kisses and caresses are done for this delectation, it follows that they are mortal sins, and only in this way are they said to be lustful. Therefore in so far as they are lustful, they are mortal sins.

Reply to Objection 1. The Apostle makes no further mention of these three because they are not sinful except as directed to those that he had mentioned before.

Reply to Objection 2. Although kisses and touches do not by their very nature hinder the good of the human offspring, they proceed from lust, which is the source of this hindrance: and on this account they are mortally sinful.

Reply to Objection 3. This argument proves that such things are not mortal sins in their species.

Article 5. Whether nocturnal pollution is a mortal sin?

_______________________________________

Objection 1. It would seem that nocturnal pollution is a sin. For the same things are the matter of merit and demerit. Now a man may merit while he sleeps, as was the case with Solomon, who while asleep obtained the gift of wisdom from the Lord (1 Sam 3:5). Therefore a man may demerit while asleep; and thus nocturnal pollution would seem to be a sin.

Objection 2. Further, whoever has the use of reason can sin. Now a man has the use of reason while asleep, since in our sleep we frequently discuss matters, choose this rather than that, consenting to one thing, or dissenting to another. Therefore one may sin while asleep, so that nocturnal pollution is not prevented by sleep from being a sin, seeing that it is a sin according to its genus.

Objection 3. Further, it is useless to reprove and instruct one who cannot act according to or against reason. Now man, while asleep, is instructed and reproved by God, according to Job 33:15-16, "By a dream in a vision by night, when deep sleep is wont to lay hold of men [Vulgate: 'When deep sleep falleth upon men.' St. Thomas is apparently quoting from memory, as the passage is given correctly above, 95, 6, Objection 1 . . . Then He openeth the ears of men, and teaching instructeth them in what they are to learn." Therefore a man, while asleep, can act according to or against his reason, and this is to do good or sinful actions, and thus it seems that nocturnal pollution is a sin.

On the contrary, Augustine says (Gen. ad lit. xii, 15): "When the same image that comes into the mind of a speaker presents itself to the mind of the sleeper, so that the latter is unable to distinguish the imaginary from the real union of bodies, the flesh is at once moved, with the result that usually follows such motions; and yet there is as little sin in this as there is in speaking and therefore thinking about such things while one is awake."

I answer that, Nocturnal pollution may be considered in two ways. First, in itself; and thus it has not the character of a sin. For every sin depends on the judgment of reason, since even the first movement of the sensuality has nothing sinful in it, except in so far as it can be suppressed by reason; wherefore in the absence of reason's judgment, there is no sin in it. Now during sleep reason has not a free judgment. For there is no one who while sleeping does not regard some of the images formed by his imagination as though they were real, as stated above in I, 84, 8, ad 2. Wherefore what a man does while he sleeps and is deprived of reason's judgment, is not imputed to him as a sin, as neither are the actions of a maniac or an imbecile.

Secondly, nocturnal pollution may be considered with reference to its cause. This may be threefold. One is a bodily cause. For when there is excess of seminal humor in the body, or when the humor is disintegrated either through overheating of the body or some other disturbance, the sleeper dreams things that are connected with the discharge of this excessive or disintegrated humor: the same thing happens when nature is cumbered with other superfluities, so that phantasms relating to the discharge of those superfluities are formed in the imagination. Accordingly if this excess of humor be due to a sinful cause (for instance excessive eating or drinking), nocturnal pollution has the character of sin from its cause: whereas if the excess or disintegration of these superfluities be not due to a sinful cause, nocturnal pollution is not sinful, neither in itself nor in its cause.

A second cause of nocturnal pollution is on the part of the soul and the inner man: for instance when it happens to the sleeper on account of some previous thought. For the thought which preceded while he was awake, is sometimes purely speculative, for instance when one thinks about the sins of the flesh for the purpose of discussion; while sometimes it is accompanied by a certain emotion either of concupiscence or of abhorrence. Now nocturnal pollution is more apt to arise from thinking about carnal sins with concupiscence for such pleasures, because this leaves its trace and inclination in the soul, so that the sleeper is more easily led in his imagination to consent to acts productive of pollution. In this sense the Philosopher says (Ethic. i, 13) that "in so far as certain movements in some degree pass" from the waking state to the state of sleep, "the dreams of good men are better than those of any other people": and Augustine says (Gen. ad lit. xii, 15) that "even during sleep, the soul may have conspicuous merit on account of its good disposition." Thus it is evident that nocturnal pollution may be sinful on the part of its cause. On the other hand, it may happen that nocturnal pollution ensues after thoughts about carnal acts, though they were speculative, or accompanied by abhorrence, and then it is not sinful, neither in itself nor in its cause.

The third cause is spiritual and external; for instance when by the work of a devil the sleeper's phantasms are disturbed so as to induce the aforesaid result. Sometimes this is associated with a previous sin, namely the neglect to guard against the wiles of the devil. Hence the words of the hymn at even: "Our enemy repress, that so our bodies no uncleanness know" [Translation W. K. Blount].

On the other hand, this may occur without any fault on man's part, and through the wickedness of the devil alone. Thus we read in the Collationes Patrum (Coll. xxii, 6) of a man who was ever wont to suffer from nocturnal pollution on festivals, and that the devil brought this about in order to prevent him from receiving Holy Communion. Hence it is manifest that nocturnal pollution is never a sin, but is sometimes the result of a previous sin.

Reply to Objection 1. Solomon did not merit to receive wisdom from God while he was asleep. He received it in token of his previous desire. It is for this reason that his petition is stated to have been pleasing to God (1 Kgs 3:10), as Augustine observes (Gen. ad lit. xii, 15).

Reply to Objection 2. The use of reason is more or less hindered in sleep, according as the inner sensitive powers are more or less overcome by sleep, on account of the violence or attenuation of the evaporations. Nevertheless it is always hindered somewhat, so as to be unable to elicit a judgment altogether free, as stated in I, 84, 8, ad 2. Therefore what it does then is not imputed to it as a sin.

Reply to Objection 3. Reason's apprehension is not hindered during sleep to the same extent as its judgment, for this is accomplished by reason turning to sensible objects, which are the first principles of human thought. Hence nothing hinders man's reason during sleep from apprehending anew something arising out of the traces left by his previous thoughts and phantasms presented to him, or again through Divine revelation, or the interference of a good or bad angel.

Article 6. Whether seduction should be reckoned a species of lust?

_______________________________________

Objection 1. It would seem that seduction should not be reckoned a species of lust. For seduction denotes the unlawful violation of a virgin, according to the Decretals (XXXVI, qu. 1) [Append. Grat. ad can. Lex illa]. But this may occur between an unmarried man and an unmarried woman, which pertains to fornication. Therefore seduction should not be reckoned a species of lust, distinct from fornication.

Objection 2. Further, Ambrose says (De Patriarch. [De Abraham i, 4): "Let no man be deluded by human laws: all seduction is adultery." Now a species is not contained under another that is differentiated in opposition to it. Therefore since adultery is a species of lust, it seems that seduction should not be reckoned a species of lust.

Objection 3. Further, to do a person an injury would seem to pertain to injustice rather than to lust. Now the seducer does an injury to another, namely the violated maiden's father, who "can take the injury as personal to himself" [Gratian, ad can. Lex illa], and sue the seducer for damages. Therefore seduction should not be reckoned a species of lust.

On the contrary, Seduction consists properly in the venereal act whereby a virgin is violated. Therefore, since lust is properly about venereal actions, it would seem that seduction is a species of lust.

I answer that, When the matter of a vice has a special deformity, we must reckon it to be a determinate species of that vice. Now lust is a sin concerned with venereal matter, as stated above (Q. 153, A. 1). And a special deformity attaches to the violation of a virgin who is under her father's care: both on the part of the maid, who through being violated without any previous compact of marriage is both hindered from contracting a lawful marriage and is put on the road to a wanton life from which she was withheld lest she should lose the seal of virginity: and on the part of the father, who is her guardian, according to Sirach 42:11, "Keep a sure watch over a shameless daughter, lest at any time she make thee become a laughing-stock to thy enemies." Therefore it is evident that seduction which denotes the unlawful violation of a virgin, while still under the guardianship of her parents, is a determinate species of lust.

Reply to Objection 1. Although a virgin is free from the bond of marriage, she is not free from her father's power. Moreover, the seal of virginity is a special obstacle to the intercourse of fornication, in that it should be removed by marriage only. Hence seduction is not simple fornication, since the latter is intercourse with harlots, women, namely, who are no longer virgins, as a gloss observes on 2 Corinthians 12, "And have not done penance for the uncleanness and fornication," etc.

Reply to Objection 2. Ambrose here takes seduction in another sense, as applicable in a general way to any sin of lust. Wherefore seduction, in the words quoted, signifies the intercourse between a married man and any woman other than his wife. This is clear from his adding: "Nor is it lawful for the husband to do what the wife may not." On this sense, too, we are to understand the words of Numbers 5:13: "If [Vulgate: 'But'] the adultery is secret, and cannot be provided by witnesses, because she was not found in adultery [stupro]."

Reply to Objection 3. Nothing prevents a sin from having a greater deformity through being united to another sin. Now the sin of lust obtains a greater deformity from the sin of injustice, because the concupiscence would seem to be more inordinate, seeing that it refrains not from the pleasurable object so that it may avoid an injustice. On fact a twofold injustice attaches to it. One is on the part of the virgin, who, though not violated by force, is nevertheless seduced, and thus the seducer is bound to compensation. Hence it is written (Ex 22:16-17): "If a man seduce a virgin not yet espoused, and lie with her, he shall endow her and have her to wife. If the maid's father will not give her to him, he shall give money according to the dowry, which virgins are wont to receive." The other injury is done to the maid's father: wherefore the seducer is bound by the Law to a penalty in his regard. For it is written (Dt 22:28-29): "If a man find a damsel that is a virgin, who is not espoused, and taking her, lie with her, and the matter come to judgment: he that lay with her shall give to the father of the maid fifty sicles of silver, and shall have her to wife, and because he hath humbled her, he may not put her away all the days of his life": and this, lest he should prove to have married her in mockery, as Augustine observes. [QQ. in Dt., qu. xxxiv.]

Article 7. Whether rape is a species of lust, distinct from seduction?

_______________________________________

Objection 1. It would seem that rape is not a species of lust, distinct from seduction. For Isidore says (Etym. v, 26) that "seduction [stuprum], or rape, properly speaking, is unlawful intercourse, and takes its name from its causing corruption: wherefore he that is guilty of rape is a seducer." Therefore it seems that rape should not be reckoned a species of lust distinct from seduction.

Objection 2. Further, rape, apparently, implies violence. For it is stated in the Decretals (XXXVI, qu. 1 [Append. Grat. ad can. Lex illa]) that "rape is committed when a maid is taken away by force from her father's house that after being violated she may be taken to wife." But the employment of force is accidental to lust, for this essentially regards the pleasure of intercourse. Therefore it seems that rape should not be reckoned a determinate species of lust.

Objection 3. Further, the sin of lust is curbed by marriage: for it is written (1 Cor 7:2): "For fear of fornication, let every man have his own wife." Now rape is an obstacle to subsequent marriage, for it was enacted in the council of Meaux: "We decree that those who are guilty of rape, or of abducting or seducing women, should not have those women in marriage, although they should have subsequently married them with the consent of their parents." Therefore rape is not a determinate species of lust distinct from seduction.

Objection 4. Further, a man may have knowledge of his newly married wife without committing a sin of lust. Yet he may commit rape if he take her away by force from her parents' house, and have carnal knowledge of her. Therefore rape should not be reckoned a determinate species of lust.

On the contrary, Rape is unlawful sexual intercourse, as Isidore states (Etym. v, 26). But this pertains to the sin of lust. Therefore rape is a species of lust.

I answer that, Rape, in the sense in which we speak of it now, is a species of lust: and sometimes it coincides with seduction; sometimes there is rape without seduction, and sometimes seduction without rape.

They coincide when a man employs force in order unlawfully to violate a virgin. This force is employed sometimes both towards the virgin and towards her father; and sometimes towards the father and not to the virgin, for instance if she allows herself to be taken away by force from her father's house. Again, the force employed in rape differs in another way, because sometimes a maid is taken away by force from her parents' house, and is forcibly violated: while sometimes, though taken away by force, she is not forcibly violated, but of her own consent, whether by act of fornication or by the act of marriage: for the conditions of rape remain no matter how force is employed. There is rape without seduction if a man abduct a widow or one who is not a virgin. Hence Pope Symmachus says [Ep. v ad Caesarium; Cf. can. Raptores xxxvi, qu. 2, "We abhor abductors whether of widows or of virgins on account of the heinousness of their crime."

There is seduction without rape when a man, without employing force, violates a virgin unlawfully.

Reply to Objection 1. Since rape frequently coincides with seduction, the one is sometimes used to signify the other.

Reply to Objection 2. The employment of force would seem to arise from the greatness of concupiscence, the result being that a man does not fear to endanger himself by offering violence.

Reply to Objection 3. The rape of a maiden who is promised in marriage is to be judged differently from that of one who is not so promised. For one who is promised in marriage must be restored to her betrothed, who has a right to her in virtue of their betrothal: whereas one that is not promised to another must first of all be restored to her father's care, and then the abductor may lawfully marry her with her parents' consent. Otherwise the marriage is unlawful, since whosoever steals a thing he is bound to restore it. Nevertheless rape does not dissolve a marriage already contracted, although it is an impediment to its being contracted. As to the decree of the council in question, it was made in abhorrence of this crime, and has been abrogated. Wherefore Jerome [The quotation is from Can. Tria. xxxvi, qu. 2 declares the contrary: "Three kinds of lawful marriage," says he, "are mentioned in Holy Writ. The first is that of a chaste maiden given away lawfully in her maidenhood to a man. The second is when a man finds a maiden in the city, and by force has carnal knowledge of her. If the father be willing, the man shall endow her according to the father's estimate, and shall pay the price of her purity [Cf. Dt 22:23-29. The third is, when the maiden is taken away from such a man, and is given to another at the father's will."

We may also take this decree to refer to those who are promised to others in marriage, especially if the betrothal be expressed by words in the present tense.

Reply to Objection 4. The man who is just married has, in virtue of the betrothal, a certain right in her: wherefore, although he sins by using violence, he is not guilty of the crime of rape. Hence Pope Gelasius says [Can. Lex illa, xxvii, qu. 2; xxxvi, qu. 1]: "This law of bygone rulers stated that rape was committed when a maiden, with regard to whose marriage nothing had so far been decided, was taken away by force."

Article 8. Whether adultery is determinate species of lust, distinct from the other species?

_______________________________________

Objection 1. It would seem that adultery is not a determinate species of lust, distinct from the other species. For adultery takes its name from a man having intercourse "with a woman who is not his own [ad alteram]," according to a gloss [St. Augustine: Serm. li, 13 de Divers. lxiii] on Exodus 20:14. Now a woman who is not one's own may be of various conditions, namely either a virgin, or under her father's care, or a harlot, or of any other description. Therefore it seems that adultery is not a species of lust distinct from the others.

Objection 2. Further, Jerome says [Contra Jovin. i]: "It matters not for what reason a man behaves as one demented. Hence Sixtus the Pythagorean says in his Maxims: He that is insatiable of his wife is an adulterer," and in like manner one who is over enamored of any woman. Now every kind of lust includes a too ardent love. Therefore adultery is in every kind of lust: and consequently it should not be reckoned a species of lust.

Objection 3. Further, where there is the same kind of deformity, there would seem to be the same species of sin. Now, apparently, there is the same kind of deformity in seduction and adultery: since in either case a woman is violated who is under another person's authority. Therefore adultery is not a determinate species of lust, distinct from the others.

On the contrary, Pope Leo [St. Augustine, De Bono Conjug. iv; Cf. Append. Grat. ad can. Ille autem. xxxii, qu. 5 says that "adultery is sexual intercourse with another man or woman in contravention of the marriage compact, whether through the impulse of one's own lust, or with the consent of the other party." Now this implies a special deformity of lust. Therefore adultery is a determinate species of lust.

I answer that, Adultery, as its name implies, "is access to another's marriage-bed [ad alienum torum]" [Cf. Append. Gratian, ad can. Ille autem. xxxii, qu. 1. By so doing a man is guilty of a twofold offense against chastity and the good of human procreation. First, by accession to a woman who is not joined to him in marriage, which is contrary to the good of the upbringing of his own children. Secondly, by accession to a woman who is united to another in marriage, and thus he hinders the good of another's children. The same applies to the married woman who is corrupted by adultery. Wherefore it is written (Sirach 23:32-33): "Every woman . . . that leaveth her husband . . . shall be guilty of sin. For first she hath been unfaithful to the law of the Most High" (since there it is commanded: "Thou shalt not commit adultery"); "and secondly, she hath offended against her husband," by making it uncertain that the children are his: "thirdly, she hath fornicated in adultery, and hath gotten children of another man," which is contrary to the good of her offspring. The first of these, however, is common to all mortal sins, while the two others belong especially to the deformity of adultery. Hence it is manifest that adultery is a determinate species of lust, through having a special deformity in venereal acts.

Reply to Objection 1. If a married man has intercourse with another woman, his sin may be denominated either with regard to him, and thus it is always adultery, since his action is contrary to the fidelity of marriage, or with regard to the woman with whom he has intercourse; and thus sometimes it is adultery, as when a married man has intercourse with another's wife; and sometimes it has the character of seduction, or of some other sin, according to various conditions affecting the woman with whom he has intercourse: and it has been stated above (A. 1) that the species of lust correspond to the various conditions of women.

Reply to Objection 2. Matrimony is specially ordained for the good of human offspring, as stated above (A. 2). But adultery is specially opposed to matrimony, in the point of breaking the marriage faith which is due between husband and wife. And since the man who is too ardent a lover of his wife acts counter to the good of marriage if he use her indecently, although he be not unfaithful, he may in a sense be called an adulterer; and even more so than he that is too ardent a lover of another woman.

Reply to Objection 3. The wife is under her husband's authority, as united to him in marriage: whereas the maid is under her father's authority, as one who is to be married by that authority. Hence the sin of adultery is contrary to the good of marriage in one way, and the sin of seduction in another; wherefore they are reckoned to differ specifically. Of other matters concerning adultery we shall speak in the Third Part [Suppl., 59, 3; Suppl., 60,62] when we treat of matrimony.

Article 9. Whether incest is a determinate species of lust?

_______________________________________

Objection 1. It would seem that incest is not a determinate species of lust. For incest ['Incestus' is equivalent to 'in-castus = 'unchaste'] takes its name from being a privation of chastity. But all kinds of lust are opposed to chastity. Therefore it seems that incest is not a species of lust, but is lust itself in general.

Objection 2. Further, it is stated in the Decretals (XXXVI, qu. 1 [Cf. Append. Grat. ad can. Lex illa]) that "incest is intercourse between a man and a woman related by consanguinity or affinity." Now affinity differs from consanguinity. Therefore it is not one but several species of lust.

Objection 3. Further, that which does not, of itself, imply a deformity, does not constitute a determinate species of vice. But intercourse between those who are related by consanguinity or affinity does not, of itself, contain any deformity, else it would never have been lawful. Therefore incest is not a determinate species of lust.

On the contrary, The species of lust are distinguished according to the various conditions of women with whom a man has unlawful intercourse. Now incest implies a special condition on the part of the woman, because it is unlawful intercourse with a woman related by consanguinity or affinity as stated (Obj. 2). Therefore incest is a determinate species of lust.

I answer that, As stated above (A1, 6) wherever we find something incompatible with the right use of venereal actions, there must needs be a determinate species of lust. Now sexual intercourse with women related by consanguinity or affinity is unbecoming to venereal union on three counts. First, because man naturally owes a certain respect to his parents and therefore to his other blood relations, who are descended in near degree from the same parents: so much so indeed that among the ancients, as Valerius Maximus relates [Dict. Fact. Memor. ii, 1, it was not deemed right for a son to bathe with his father, lest they should see one another naked. Now from what has been said (142, 4; 151, 4), it is evident that in venereal acts there is a certain shamefulness inconsistent with respect, wherefore men are ashamed of them. Wherefore it is unseemly that such persons should be united in venereal intercourse. This reason seems to be indicated (Lev 18:7) where we read: "She is thy mother, thou shalt not uncover her nakedness," and the same is expressed further on with regard to others.

The second reason is because blood relations must needs live in close touch with one another. Wherefore if they were not debarred from venereal union, opportunities of venereal intercourse would be very frequent and thus men's minds would be enervated by lust. Hence in the Old Law [Lev 18] the prohibition was apparently directed specially to those persons who must needs live together.

The third reason is, because this would hinder a man from having many friends: since through a man taking a stranger to wife, all his wife's relations are united to him by a special kind of friendship, as though they were of the same blood as himself. Wherefore Augustine says (De Civ. Dei xv, 16): "The demands of charity are most perfectly satisfied by men uniting together in the bonds that the various ties of friendship require, so that they may live together in a useful and becoming amity; nor should one man have many relationships in one, but each should have one."

Aristotle adds another reason (2 Polit. ii): for since it is natural that a man should have a liking for a woman of his kindred, if to this be added the love that has its origin in venereal intercourse, his love would be too ardent and would become a very great incentive to lust: and this is contrary to chastity. Hence it is evident that incest is a determinate species of lust.

Reply to Objection 1. Unlawful intercourse between persons related to one another would be most prejudicial to chastity, both on account of the opportunities it affords, and because of the excessive ardor of love, as stated in the Article. Wherefore the unlawful intercourse between such persons is called "incest" antonomastically.

Reply to Objection 2. Persons are related by affinity through one who is related by consanguinity: and therefore since the one depends on the other, consanguinity and affinity entail the same kind of unbecomingness.

Reply to Objection 3. There is something essentially unbecoming and contrary to natural reason in sexual intercourse between persons related by blood, for instance between parents and children who are directly and immediately related to one another, since children naturally owe their parents honor. Hence the Philosopher instances a horse (De Animal. ix, 47) which covered its own mother by mistake and threw itself over a precipice as though horrified at what it had done, because some animals even have a natural respect for those that have begotten them. There is not the same essential unbecomingness attaching to other persons who are related to one another not directly but through their parents: and, as to this, becomingness or unbecomingness varies according to custom, and human or Divine law: because, as stated above (A. 2), sexual intercourse, being directed to the common good, is subject to law. Wherefore, as Augustine says (De Civ. Dei xv, 16), whereas the union of brothers and sisters goes back to olden times, it became all the more worthy of condemnation when religion forbade it.

Article 10. Whether sacrilege can be a species of lust?

_______________________________________

Objection 1. It would seem that sacrilege cannot be a species of lust. For the same species is not contained under different genera that are not subalternated to one another. Now sacrilege is a species of irreligion, as stated above (Q. 99, A. 2). Therefore sacrilege cannot be reckoned a species of lust.

Objection 2. Further, the Decretals (XXXVI, qu. 1 [Append. Grat. ad can. Lex illa]), do not place sacrilege among other sins which are reckoned species of lust. Therefore it would seem not to be a species of lust.

Objection 3. Further, something derogatory to a sacred thing may be done by the other kinds of vice, as well as by lust. But sacrilege is not reckoned a species of gluttony, or of any other similar vice. Therefore neither should it be reckoned a species of lust.

On the contrary, Augustine says (De Civ. Dei xv, 16) that "if it is wicked, through covetousness, to go beyond one's earthly bounds, how much more wicked is it through venereal lust to transgress the bounds of morals!" Now to go beyond one's earthly bounds in sacred matters is a sin of sacrilege. Therefore it is likewise a sin of sacrilege to overthrow the bounds of morals through venereal desire in sacred matters. But venereal desire pertains to lust. Therefore sacrilege is a species of lust.

I answer that, As stated above (I-II, 18, 6,7), the act of a virtue or vice, that is directed to the end of another virtue or vice, assumes the latter's species: thus, theft committed for the sake of adultery, passes into the species of adultery. Now it is evident that as Augustine states (De Virgin. 8), the observance of chastity, by being directed to the worship of God, becomes an act of religion, as in the case of those who vow and keep chastity. Wherefore it is manifest that lust also, by violating something pertaining to the worship of God, belongs to the species of sacrilege: and in this way sacrilege may be accounted a species of lust.

Reply to Objection 1. Lust, by being directed to another vice as its end, becomes a species of that vice: and so a species of lust may be also a species of irreligion, as of a higher genus.

Reply to Objection 2. The enumeration referred to, includes those sins which are species of lust by their very nature: whereas sacrilege is a species of lust in so far as it is directed to another vice as its end, and may coincide with the various species of lust. For unlawful intercourse between persons mutually united by spiritual relationship, is a sacrilege after the manner of incest. Intercourse with a virgin consecrated to God, inasmuch as she is the spouse of Christ, is sacrilege resembling adultery. If the maiden be under her father's authority, it will be spiritual seduction; and if force be employed it will be spiritual rape, which kind of rape even the civil law punishes more severely than others. Thus the Emperor Justinian says [Cod. i, iii de Episc. et Cler. 5: "If any man dare, I will not say to rape, but even to tempt a consecrated virgin with a view to marriage, he shall be liable to capital punishment."

Reply to Objection 3. Sacrilege is committed on a consecrated thing. Now a consecrated thing is either a consecrated person, who is desired for sexual intercourse, and thus it is a kind of lust, or it is desired for possession, and thus it is a kind of injustice. Sacrilege may also come under the head of anger, for instance, if through anger an injury be done to a consecrated person. Again, one may commit a sacrilege by partaking gluttonously of sacred food. Nevertheless, sacrilege is ascribed more specially to lust which is opposed to chastity for the observance of which certain persons are specially consecrated.

Article 11. Whether the unnatural vice is a species of lust?

_______________________________________

Objection 1. It would seem that the unnatural vice is not a species of lust. For no mention of the vice against nature is made in the enumeration given above (1, Obj. 1). Therefore it is not a species of lust.

Objection 2. Further, lust is contrary to virtue; and so it is comprised under vice. But the unnatural vice is comprised not under vice, but under bestiality, according to the Philosopher (Ethic. vii, 5). Therefore the unnatural vice is not a species of lust.

Objection 3. Further, lust regards acts directed to human generation, as stated above (Q. 153, A. 2): Whereas the unnatural vice concerns acts from which generation cannot follow. Therefore the unnatural vice is not a species of lust.

On the contrary, It is reckoned together with the other species of lust (2 Cor 12:21) where we read: "And have not done penance for the uncleanness, and fornication, and lasciviousness," where a gloss says: "Lasciviousness, i.e., unnatural lust."

I answer that, As stated above (A6, 9) wherever there occurs a special kind of deformity whereby the venereal act is rendered unbecoming, there is a determinate species of lust. This may occur in two ways: First, through being contrary to right reason, and this is common to all lustful vices; secondly, because, in addition, it is contrary to the natural order of the venereal act as becoming to the human race: and this is called "the unnatural vice." This may happen in several ways. First, by procuring pollution, without any copulation, for the sake of venereal pleasure: this pertains to the sin of "uncleanness" which some call "effeminacy." Secondly, by copulation with a thing of undue species, and this is called "bestiality." Thirdly, by copulation with an undue sex, male with male, or female with female, as the Apostle states (Rom 1:27): and this is called the "vice of sodomy." Fourthly, by not observing the natural manner of copulation, either as to undue means, or as to other monstrous and bestial manners of copulation.

Reply to Objection 1. There we enumerated the species of lust that are not contrary to human nature: wherefore the unnatural vice was omitted.

Reply to Objection 2. Bestiality differs from vice, for the latter is opposed to human virtue by a certain excess in the same matter as the virtue, and therefore is reducible to the same genus.

Reply to Objection 3. The lustful man intends not human generation but venereal pleasures. It is possible to have this without those acts from which human generation follows: and it is that which is sought in the unnatural vice.

Article 12. Whether the unnatural vice is the greatest sin among the species of lust?

_______________________________________

Objection 1. It would seem that the unnatural vice is not the greatest sin among the species of lust. For the more a sin is contrary to charity the graver it is. Now adultery, seduction and rape which are injurious to our neighbor are seemingly more contrary to the love of our neighbor, than unnatural sins, by which no other person is injured. Therefore the unnatural sin is not the greatest among the species of lust.

Objection 2. Further, sins committed against God would seem to be the most grievous. Now sacrilege is committed directly against God, since it is injurious to the Divine worship. Therefore sacrilege is a graver sin than the unnatural vice.

Objection 3. Further, seemingly, a sin is all the more grievous according as we owe a greater love to the person against whom that sin is committed. Now the order of charity requires that a man love more those persons who are united to him—and such are those whom he defiles by incest—than persons who are not connected with him, and whom in certain cases he defiles by the unnatural vice. Therefore incest is a graver sin than the unnatural vice.

Objection 4. Further, if the unnatural vice is most grievous, the more it is against nature the graver it would seem to be. Now the sin of uncleanness or effeminacy would seem to be most contrary to nature, since it would seem especially in accord with nature that agent and patient should be distinct from one another. Hence it would follow that uncleanness is the gravest of unnatural vices. But this is not true. Therefore unnatural vices are not the most grievous among sins of lust.

On the contrary, Augustine says (De adult. conjug. [The quotation is from Cap. Adulterii xxxii, qu. 7. Cf. Augustine, De Bono Conjugali, viii.]) that "of all these," namely the sins belonging to lust, "that which is against nature is the worst."

I answer that, In every genus, worst of all is the corruption of the principle on which the rest depend. Now the principles of reason are those things that are according to nature, because reason presupposes things as determined by nature, before disposing of other things according as it is fitting. This may be observed both in speculative and in practical matters. Wherefore just as in speculative matters the most grievous and shameful error is that which is about things the knowledge of which is naturally bestowed on man, so in matters of action it is most grave and shameful to act against things as determined by nature. Therefore, since by the unnatural vices man transgresses that which has been determined by nature with regard to the use of venereal actions, it follows that in this matter this sin is gravest of all. After it comes incest, which, as stated above (A. 9), is contrary to the natural respect which we owe persons related to us.

With regard to the other species of lust they imply a transgression merely of that which is determined by right reason, on the presupposition, however, of natural principles. Now it is more against reason to make use of the venereal act not only with prejudice to the future offspring, but also so as to injure another person besides. Wherefore simple fornication, which is committed without injustice to another person, is the least grave among the species of lust. Then, it is a greater injustice to have intercourse with a woman who is subject to another's authority as regards the act of generation, than as regards merely her guardianship. Wherefore adultery is more grievous than seduction. And both of these are aggravated by the use of violence. Hence rape of a virgin is graver than seduction, and rape of a wife than adultery. And all these are aggravated by coming under the head of sacrilege, as stated above (10, ad 2).

Reply to Objection 1. Just as the ordering of right reason proceeds from man, so the order of nature is from God Himself: wherefore in sins contrary to nature, whereby the very order of nature is violated, an injury is done to God, the Author of nature. Hence Augustine says (Confess. iii, 8): "Those foul offenses that are against nature should be everywhere and at all times detested and punished, such as were those of the people of Sodom, which should all nations commit, they should all stand guilty of the same crime, by the law of God which hath not so made men that they should so abuse one another. For even that very intercourse which should be between God and us is violated, when that same nature, of which He is the Author, is polluted by the perversity of lust."

Reply to Objection 2. Vices against nature are also against God, as stated above (ad 1), and are so much more grievous than the depravity of sacrilege, as the order impressed on human nature is prior to and more firm than any subsequently established order.

Reply to Objection 3. The nature of the species is more intimately united to each individual, than any other individual is. Wherefore sins against the specific nature are more grievous.

Reply to Objection 4. Gravity of a sin depends more on the abuse of a thing than on the omission of the right use. Wherefore among sins against nature, the lowest place belongs to the sin of uncleanness, which consists in the mere omission of copulation with another. While the most grievous is the sin of bestiality, because use of the due species is not observed. Hence a gloss on Genesis 37:2, "He accused his brethren of a most wicked crime," says that "they copulated with cattle." After this comes the sin of sodomy, because use of the right sex is not observed. Lastly comes the sin of not observing the right manner of copulation, which is more grievous if the abuse regards the "vas" than if it affects the manner of copulation in respect of other circumstances.

+ + +
Source: The Summa Theologica of St. Thomas Aquinas
Second and Revised Edition, 1920
Literally translated by Fathers of the English Dominican Province