It is not to be forgotten that what we call rational grounds for our beliefs are often extremely irrational attempts to justify our instincts.

I do not say think as I think, but think in my way. Fear no shadows, least of all in that great spectre of personal unhappiness which binds half the world to orthodoxy.

The scientific spirit is of more value than its products, and irrationally held truths may be more harmful than reasoned errors.

Books are the money of Literature, but only the counters of Science.

I believe that history might be, and ought to be, taught in a new fashion so as to make the meaning of it as a process of evolution intelligible to the young.

Surely there is a time to submit to guidance and a time to take one's own way at all hazards.

Nothing can be more incorrect than the assumption one sometimes meets with, that physics has one method, chemistry another, and biology a third.