Man has no moral instinct. He is not born with moral sense. You were not born with it, I was not - and a puppy has none. We acquire moral sense, when we do, through training, experience, and hard sweat of the mind.
Robert A. HeinleinSex, whatever else it is, is an athletic skill. The more you practice, the more you can, the more you want to, the more you enjoy it, the less it tires you.
Robert A. Heinlein