Letters 94.24

“Nothing,” it is said, “will be accomplished by applying advice to the more serious faults.” No; and not even medicine can master incurable diseases; it is nevertheless used in some cases as a remedy, in others as a relief. Not even the power of universal philosophy, though it summon all its strength for the purpose, will remove from the soul what is now a stubborn and chronic disease. But Wisdom, merely because she cannot cure everything, is not incapable of making cures.

Seneca, Letters to Lucilius 94.24, translated by Richard Mott Gummere