I have never entered into any controversy in defense of my philosophical opinions; I leave them to take their chance in the world. If they are right, truth and experience will support them; if wrong, they ought to be refuted and rejected. Disputes are apt to sour one's temper and disturb one's quiet.
The answer to old age is to keep one's mind busy and to go on with one's life as if it were interminable. I always admired Chekhov for building a new house when he was dying of tuberculosis.
