Letters 72.9

The happiness that he enjoys is supremely great, is lasting, is his own. Assume that a man has good intentions, and has made progress, but is still far from the heights; the result is a series of ups and downs; he is now raised to heaven, now brought down to earth. For those who lack experience and training, there is no limit to the downhill course; such a one falls into the Chaos of Epicurus,—empty and boundless.

Seneca, Letters to Lucilius 72.9, translated by Richard Mott Gummere