I always feel that I have two duties to perform with a parting guest: one, to see that he doesn't forget anything that is his; the other, to see that he doesn't take anything that is mine.

You cannot evade quantity. You may fly to poetry and music, and quantity and number will face you in your rhythms and your octaves.

Error itself may be happy chance.

There are no whole truths: all truths are half-truths. It is trying to treat them as whole truths that plays to the devil.

On the ostensible exactitude of certain branches of human knowledge, including mathematics. The exactness is a fake.

How the past perishes is how the future becomes.

That knowledge which adds greatness to character is knowledge so handled as to transform every phase of immediate experience.