Letters 25.6

And when you have progressed so far that you have also respect for yourself, you may send away your attendant; but until then, set as a guard over yourself the authority of some man, whether your choice be the great Cato or Scipio, or Laelius,—or any man in whose presence even abandoned wretches would check their bad impulses. Meantime, you are engaged in making of yourself the sort of person in whose company you would not dare to sin. When this aim has been accomplished and you begin to hold yourself in some esteem, I shall gradually allow you to do what Epicurus, in another passage, suggests: “The time when you should most of all withdraw into yourself is when you are forced to be in a crowd.”

Seneca, Letters to Lucilius 25.6, translated by Richard Mott Gummere