Common sense is science exactly in so far as it fulfills the ideal of common sense; that is, sees facts as they are, or at any rate, without the distortion of prejudice, and reasons from them in accordance with the dictates of sound judgment. And science is simply common sense at its best, that is, rigidly accurate in observation, and merciless to fallacy in logic.

I am content with nothing, restless and ambitious... and I despise myself for the vanity, which formed half the stimulus to my exertions. Oh would that I were one of those plodding wise fools who having once set their hand to the plough go on nothing doubting.

I'd rather have an ape for an ancestor than a bishop.

Logical consequences are the scarecrows of fools and the beacons of wise men.

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.

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.

It is given to few to add the store of knowledge, to strike new springs of thought, or to shape new forms of beauty. But so sure as it is that men live not by bread, but by ideas, so sure is it that the future of the world lies in the hands of those who are able to carry the interpretation of nature a step further than their predecessors.