The soul has two parts, one rational and the other irrational. Let us now similarly divide the rational part, and let it be assumed that there are two rational faculties, one whereby we contemplate those things whose first principles are invariable, and one whereby we contemplate those things which admit of variation.
AristotleAs the pleasures of the body are the ones which we most often meet with, and as all men are capable of these, these have usurped the family title; and some men think these are the only pleasures that exist, because they are the only ones which they know.
Aristotle