Plutarch, De communibus notitiis adversus Stoicos
Goodwin, Ed.

Now, forasmuch as all men esteem the sovereign good to be joyous, desirable, happy, of the greatest dignity, self-sufficient, and wanting nothing; compare their good, and see how it agrees with this common conception. Does the stretching out a finger prudently produce this joy? Is a prudent torture a thing desirable? Is he happy, who with reason breaks his neck? Is that of the greatest dignity, which reason often chooses to let go for that which is not good? Is that perfect and self-sufficient, by enjoying which, if they have not also indifferent things, they neither can nor will endure to live? There is also [p. 395] another principle of the Stoics, by which custom is still more injured, taking and plucking from her genuine notions, which are as her legitimate children, and supposing other bastardly, wild, and illegitimate ones in their room, and necessitating her to nourish and cherish the one instead of the other; and that too in those doctrines which concern things good and bad, desirable and avoidable, proper and strange, the energy of which ought to be more clearly distinguished than that of hot and cold, black and white. For the imaginations of these things are brought in by the senses from without; but those have their original bred from the good things which we have within us. But these men entering with their logic upon the topic of felicity, as on the sophism called Pseudomenos, or that named Kyrieuon, have removed no ambiguities, but brought in very many.