'Why not say that the meaning and purpose of the sexual powers is pleasure? Certainly sex is pleasurable, but there is nothing distinctive about that. In various ways and degrees, the exercise of every voluntary power is pleasurable. It is pleasurable to eat, pleasurable to breathe, even pleasurable to flex the muscles of the leg. The problem is that eating is pleasurable even if I am eating too much, breathing is pleasurable even if I am sniffing glue, flexing the muscles is pleasurable even if I am kicking the dog. For a criterion of when it is good to enjoy each pleasure, one must look beyond the fact that it is a pleasure.'
J Budziszewski, On the Meaning of Sex, p.24.