“NO EVIL as such can be desirable, either by natural appetite or by conscious will. It is sought indirectly, namely because it is a consequence of some good. This is the rule for every type of appetite. A natural force works for a form, not the absence of form. Yet one form may extrude another. A lion kills for food, that means the death of the deer; a fornicator wants pleasure, and incurs the deformity of sin.”
~St. Thomas Aquinas: Summa Theologica, I, q. 19, a. 9.
(Thomas Gilby's translation)
