A man should look for what is, and not for what he thinks should be.

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.

Mere unbelief in a personal God is no philosophy at all.

In my personal experience I have hardly come to know the wretchedness of mankind better than as a result of the general theory of relativity and everything connected to it. But it doesn't bother me.

It would of course be a great step forward if we succeeded in combining the gravitational field and the electromagnetic field into a single structure. Only so could the era in theoretical physics inaugurated by Faraday and James Clerk Maxwell be brought to a satisfactory close.

Compassionate people are geniuses in the art of living, more necessary to the dignity, security, and joy of humanity than the discoverers of knowledge.

Force always attracts men of low morality.