He who abstains from the pleasures of the body and rejoices in the abstinence is temperate, while he who is vexed at having to abstain is profligate; and again, he who faces danger with pleasure, or, at any rate, without pain, is courageous, but he to whom this is painful is a coward.

For moral virtue or excellence is closely concerned with pleasure and pain. It is pleasure that moves us to do what is base, and pain that moves us to refrain from what is noble. And therefore, as Plato says, man needs to be so trained from his youth up as to find pleasure and pain in the right objects. This is what sound education means.

Another reason why virtue has to do with pleasure and pain, is that it has to do with actions and passions or affections; but every affection and every act is accompanied by pleasure or pain.

The fact is further attested by the employment of pleasure and pain in correction; they have a kind of curative property, and a cure is effected by administering the opposite of the disease.