Letters 124.2

Those who rate pleasure as the supreme ideal hold that the Good is a matter of the senses; but we Stoics maintain that it is a matter of the understanding, and we assign it to the mind. If the senses were to pass judgment on what is good, we should never reject any pleasure; for there is no pleasure that does not attract, no pleasure that does not please. Conversely, we should undergo no pain voluntarily; for there is no pain that does not clash with the senses.

Seneca, Letters to Lucilius 124.2, translated by Richard Mott Gummere