The Bible may be the truth, but it is not the whole truth and nothing but the truth.

Whereas, to borrow an illustration from mathematics, life was formerly an equation of, say, 100 unknown quantities, it is now one of 99 only, inasmuch as memory and heredity have been shown to be one and the same thing.

Though analogy is often misleading, it is the least misleading thing we have.

There are two classes [of scientists], those who want to know, and do not care whether others think they know or not, and those who do not much care about knowing, but care very greatly about being reputed as knowing.

All animals, except man, know that the principal business of life is to enjoy it - and they do enjoy it as much as man and other circumstances will allow.

I am the enfant terrible of literature and science. If I cannot, and I know I cannot, get the literary and scientific bigwigs to give me a shilling, I can, and I know I can, heave bricks into the middle of them.

There is no such source of error as the pursuit of absolute truth.