" That which is in itself in accordance with nature, or which produces something else that is so, and which therefore is deserving of choice as possessing a certain amount of positive value—axia as the Stoics call it—this they pronounce to be ‘valuable’ (for so I suppose we may translate it); and on the other hand that which is the contrary of the former they term ‘valueless.’ The initial principle being thus established that things in accordance with nature are ‘things to be taken’ for their own sake, and their opposites similarly ‘things to be rejected,’ the first ‘appropriate act’ (for so I render the Greek kathekon) is to preserve oneself in one’s natural constitution; the next is to retain those things which are in accordance with nature and to repel those that are contrary; then when this principle of choice and also of rejection has been discovered, there follows next in order choice conditioned by ‘appropriate action’; then such choice become a fixed habit; and finally, choice fully rationalized and in harmony with nature. "

― Marcus Tullius Cicero , On Ends (De finibus bonorum et malorum)