Letters 106.7

and so also are goods, first because they are opposite poles of the bad, and second because they will manifest to you the same symptoms. Do you not see how a spirit of bravery makes the eye flash? How prudence tends towards concentration? How reverence produces moderation and tranquillity? How joy produces calm? How sternness begets stiffness? How gentleness produces relaxation? These qualities are therefore bodily; for they change the tones and the shapes of substances, exercising their own power in their own kingdoms.

Now all the virtues which I have mentioned are goods, and so are their results.

Seneca, Letters to Lucilius 106.7, translated by Richard Mott Gummere