Letters 98.17

This, my dear Lucilius, is what we mean by studying philosophy while applying it, by practising it on truth—note what courage a prudent man possesses against death, or against pain, when the one approaches and the other weighs heavily. What ought to be done must be learned from one who does it.

Seneca, Letters to Lucilius 98.17, translated by Richard Mott Gummere