If we don't end war, war will end us.

When the mind grapples with a great and intricate problem, it makes its advances step by step, with but little realization of the gains it has made, until suddenly, with an effect of abrupt illumination, it realizes its victory.

This has ever been the fate of energy in security; it takes to art and to eroticism, and then comes languor and decay.

You must follow me carefully. I shall have to controvert one or two ideas that are almost universally accepted. The geometry, for instance, they taught you at school is founded on a misconception.

There is no reason whatever to believe that the order of nature has any greater bias in favour of man than it had in favour of the ichthyosaur or the pterodactyl.

I write to cover a frame of ideas.

An immense and ever-increasing wealth of knowledge is scattered about the world today; knowledge that would probably suffice to solve all the mighty difficulties of our age, but it is dispersed and unorganized. We need a sort of mental clearing house for the mind: a depot where knowledge and ideas are received, sorted, summarized, digested, clarified and compared.