σωφροσύνη is one of the four cardinal TERMvirtues (with TERMφρόνησις, δικαιοσύνη, ἀνδρεία). Etymologically from σῶς + φρήν, "sound mind," "unimpaired reason"; hence the double sense: "prudence" (the soundness of judgment) and "temperance" (self-command in desire).

The Stoic definition: ἐπιστήμη αἱρετῶν καὶ φευκτῶν καὶ οὐδετέρων — "the knowledge of what is to be chosen, what avoided, and what is neither." That is, σωφροσύνη is TERMφρόνησις applied to the domain of impulse (ὁρμή) and appetite (TERMἐπιθυμία): it keeps the impulses in measure, subordinate to right reason, and does not let pleasure distort the valuation. Since for the Stoics virtue is knowledge, σωφροσύνη is not the suppression of the passions by will but the correct judgment of value, in which the irrational expansion of the soul simply does not arise.

SVF III 262 ff., 264–266 (the doctrine of the four virtues); DL VII 92–93 (the definitions of the cardinal virtues); Stob. Ecl. II 59–60 W; Cic. De off. I; LS 61. The Platonic background: Resp. IV 430e–432a (σωφροσύνη as the concord of the parts of the soul). In Marcus, in the lists of the cardinal virtues: Med. 3.6 (truth, justice, temperance, fortitude); 05-12; 07-63 (souls are deprived of σωφροσύνη too against their will — as of truth).