Letters 68.14

“And when,” you ask, “will that profit you which you do not learn until your departure, and how will it profit you?” Precisely in this way, that I shall depart a better man. You need not think, however, that any time of life is more fitted to the attainment of a sound mind than that which has gained the victory over itself by many trials and by long and oft-repeated regret for past mistakes, and, its passions assuaged, has reached a state of health. This is indeed the time to have acquired this good; he who has attained wisdom in his old age, has attained it by his years. Farewell.

Seneca, Letters to Lucilius 68.14, translated by Richard Mott Gummere