Hiero (1.5-1.6)

In the case of cold and heat, things hard and soft, light and heavy, our sensations of pleasure and pain depend on the whole body, I think. In good and evil we seem to feel pleasure or pain, as the case may be—sometimes through the instrumentality of the moral being only, at other times through that of the moral and the physical being together.

Sleep, it seems clear to me, affects us with pleasure; but how and by what means and when are puzzles that I feel less able to solve. And perhaps it is no matter for surprise if our sensations are clearer when we are awake than when we are asleep.