A habit of basing convictions upon evidence, and of giving to them only that degree or certainty which the evidence warrants, would, if it became general, cure most of the ills from which the world suffers.

Orthodoxy is the grave of intelligence, no matter what orthodoxy it may be.

I used, when I was younger, to take my holidays walking. I would cover 25 miles a day, and when the evening came I had no need of anything to keep me from boredom, since the delight of sitting amply sufficed.

In the visible world, the Milky Way is a tiny fragment; within this fragment, the solar system is an infinitesimal speck, and of this speck our planet is a microscopic dot. On this dot, tiny lumps of impure carbon and water, of complicated structure, with somewhat unusual physical and chemical properties, crawl about for a few years, until they are dissolved again into the elements of which they are compounded.

More cranks take up unfashionable errors than unfashionable truths.

The main thing needed to make men happy is intelligence.

If you wish to be happy yourself, you must resign yourself to seeing others also happy.