I consider the official Catholic attitude on divorce, birth control, and censorship exceedingly dangerous to mankind.

Reason may be a small force, but it is constant, and works always in one direction, while the forces of unreason destroy one another in futile strife.

We know too much and feel too little.

If I were granted omnipotence, and millions of years to experiment in, I should not think Man much to boast of as the final result of all my efforts.

The main thing needed to make men happy is intelligence.

When we perceive any object of a familiar kind, much of what appears subjectively to be immediately given is really derived from past experience.

You must believe that you can help bring about a better world.