When I examine myself and my methods of thought, I come to the conclusion that the gift of fantasy has meant more to me than my talent for absorbing positive knowledge. (Reading this makes me wonder how much sooner man could have walked on the moon... had we listened to a child's fantasies. It is truly a pity that so many lose their gift of imagination to the steady hum of the status quo.)

You do not really understand something unless you can explain it to your grandmother.

What is essential in the life of a man of my kind is what he thinks and how he thinks, and not what he does or suffers.

To the extent math refers to reality, we are not certain to the extent we are certain, math does not refer to reality.

If people are good because they fear punishment, and hope for reward, then we are a sorry lot indeed.

Concern for man himself and his fate must always form the chief interest of all technical endeavors, concern for the great unsolved problems of the organization of labor and the distribution of goods-in order that the creations of our mind shall be a blessing and not a curse to mankind. Never forget this in the midst of your diagrams and equations.

Somebody who only reads newspapers and at best books of contemporary authors looks to me like an extremely near-sighted person who scorns eyeglasses. He is completely dependent on the prejudices and fashions of his times, since he never gets to see or hear anything else.