Greek φρόνησις (phronēsis); Latin prudentia
Prudence or practical wisdom, which Epicurus calls the greatest good among the means to a pleasant life, more precious even than philosophy, and the source of all the other virtues.
1. Key Texts
Quote from Epicurus, Letter to Menoeceus 132 (Prudence as the Root of All Virtues)Of all this the beginning and the greatest good is prudence. Therefore prudence is even more precious than philosophy, and it is the natural source of all the remaining virtues; it teaches the impossibility of living pleasurably without living prudently, honorably and justly, and the impossibility of living prudently, honorably and justly without living pleasurably. For the virtues are naturally linked with living pleasurably, and living pleasurably is inseparable from them. (Bailey)