Life is like a bicycle; keep moving on to maintain balance.

The most precious things in life are not those you get for money.

Pure mathematics is, in its way, the poetry of logical ideas. ... [By seeking] logical beauty spiritual formulas are discovered necessary for the deeper penetration into the laws of nature.

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

My interest in science was always essentially limited to the study of principles.... That I have published so little is due to this same circumstance, as the great need to grasp principles has caused me to spend most of my time on fruitless pursuits.

God did not create evil. Just as darkness is the absence of light, evil is the absence of God.

It is also a natural thing for a serious young man that he should form for himself as precise an idea as possible of the goal of his desires.