Sôphrosunê is the Greek virtue of self-control, or temperance, a virtue that Aristotle says lies between self-indulgence (akolasia) on the one hand and insensibility (anaisthêsia) on the other. In its earliest uses (Homer) the word means "soundness of mind," "prudence," "discretion," and is related to the verb sôphronein, combining sôs, safe, and phronein, to think, a verb related to phrên, an archaism for mind (literally, "midriff," "heart," "the seat of thought," according to the Greeks).

Although Plato dedicated an entire dialogue (Charmides) to a discussion of the meaning of sôphrosunê, the notion of self-mastery is central to his ethical theory and he invokes it in many contexts, ranging from the Gorgias to the Republic to the Laws. Plato's central claim is that self-mastery is more than the mere abstention from certain forms...