“NOT every love has the quality of friendship. In the first place it is reserved to that love for another which wills his well-being. When what we will is not the other’s good for his sake, but the desire of it as it affects us, that is not friendship, but self-regarding love and some sort of concupiscence. Neither does benevolence suffice for friendship; in addition a mutual loving is required, for a friend is friend to friend. This interplay of well-wishing is founded on companionship.”
~St. Thomas Aquinas: Summa Theologica, II-II, q. 23, a. 4.
(Thomas Gilby's translation)
