Letters 66.29

Accordingly, if all the virtues are by nature equal, the three varieties of goods are equal. This is what I mean: there is an equality between feeling joy with self-control and suffering pain with self-control. The joy in the one case does not surpass in the other the steadfastness of soul that gulps down the groan when the victim is in the clutches of the torturer; goods of the first kind are desirable, while those of the second are worthy of admiration; and in each case they are none the less equal, because whatever inconvenience attaches to the latter is compensated by the qualities of the good, which is so much greater.

Seneca, Letters to Lucilius 66.29, translated by Richard Mott Gummere