DL 6.7 · Antisthenes
Being asked what learning is the most necessary, he replied, "How to get rid of having anything to unlearn." And he advised that when men are slandered, they should endure it more courageously than if they were pelted with stones. And he used to taunt Plato with being conceited. At all events when in a procession he spied a spirited charger he said, turning to Plato, "It seems to me that you would have made just such a proud, showy steed." This because Plato was constantly praising horseflesh. And one day he visited Plato, who was ill, and seeing the basin into which Plato had vomited, remarked, "The bile I see, but not the pride."