Insight, untested and unsupported, is an uncertain guarantee of the truth.

Man can be scientifically manipulated.

What is best in mathematics deserves not merely to be learnt as a task, but to assimilated as a part of daily thought, and brought again and again before the mind with ever-renewed encouragement.

Machines deprive us of two things which are certainly important ingredients of human happiness, namely, spontaneity and variety.

The triumph of science has been mainly due to its practical utility, and there has been an attempt to divorce this aspect from that of theory, thus making science more and more a technique, and less and less a doctrine as to the nature of the world. The penetration of this point of view to philosophers is very recent.

My own belief is that in most ages and in most places obscure psychological forces led men to adopt systems involving quite unnecessary cruelty, and that this is still the case among the most civilized races at the present day.

I have come to realize that an early symptom of approaching mental illness is the belief that one's work is terribly important. If you consider your work very important you should take a day off.