You have been inquiring about our friend Marcellinus and you desire to know how he is getting along. He seldom comes to see me, for no other reason than that he is afraid to hear the truth, and at present he is removed from my danger of hearing it; for one must not talk to a man unless he is willing to listen. That is why it is often doubted whether Diogenes and the other Cynics, who employed an undiscriminating freedom of speech and offered advice to any who came in their way, ought to have pursued such a plan. For what if one should chide the deaf or those who are speechless from birth or by illness? But you answer: Why should I spare words? They cost nothing. I cannot know whether I shall help the man to whom I give advice; but I know well that I shall help someone if I advise many. I must scatter this advice by the handful./a It is impossible that one who tries often should not sometime succeed.“
Source: Lucius Annaeus Seneca. Moral Epistles. Translated by Richard M. Gummere. The Loeb Classical Library. Cambridge, Mass.: Harvard UP, 1917-25.