“Genius is the ability to put into effect what is on your mind.”

“The test of a first-rate intelligence is the ability to hold two opposed ideas in the mind at the same time, and still retain the ability to function.”

“Vitality shows not only in the ability to persist, but in the ability to start over.”

“Before I go on with this short history, let me make a general observation– the test of a first-rate intelligence is the ability to hold two opposed ideas in the mind at the same time, and still retain the ability to function.One should, for example, be able to see that things are hopeless and yet be determined to make them otherwise. This philosophy fitted on to my early adult life, when I saw the improbable, the implausible, often the "impossible," come true.”

“That however the brains and abilities of men may differ, their stomachs are essentially the same.”

“All thought usually reached the public after thirty years in some such form: The man on the street heard the conclusions of some dead genius through someone else's clever paradoxes and didactic epigrams.”

“You are bound to go up and down, just as I did in my youth, but do keep your clarity of mind, and if fools or sages dare to criticise don't blame yourself too much.”