Letters 88.4

The question is: do such men teach virtue, or not? If they do not teach it, then neither do they transmit it. If they do teach it, they are philosophers. Would you like to know how it happens that they have not taken the chair for the purpose of teaching virtue? See how unlike their subjects are; and yet their subjects would resemble each other if they taught the same thing.

Seneca, Letters to Lucilius 88.4, translated by Richard Mott Gummere