Letters 92.8

The irrational part of the soul is twofold: the one part is spirited, ambitious, uncontrolled; its seat is in the passions; the other is lowly, sluggish, and devoted to pleasure. Philosophers have neglected the former, which, though unbridled, is yet better, and is certainly more courageous and more worthy of a man, and have regarded the latter, which is nerveless and ignoble, as indispensable to the happy life.

Seneca, Letters to Lucilius 92.8, translated by Richard Mott Gummere