The besetting sin of able men is impatience of contradiction and of criticism. Even those who do their best to resist the temptation, yield to it almost unconsciously and become the tools of toadies and flatterers. "Authorities," "disciples," and "schools" are the curse of science and do more to interfere with the work of the scientific spirit than all its enemies.

My belief is that no human being or society composed of human beings ever did or ever will come to much unless their conduct was governed and guided by the love of some ethical ideal.

Better live a crossing-sweeper than die and be made to talk twaddle by a "medium" hired at a guinea a seance.

In the world of letters, learning and knowledge are one, and books are the source of both; whereas in science, as in life, learning and knowledge are distinct, and the study of things, and not of books, is the source of the latter.

Of moral purpose I see no trace in Nature. That is an article of exclusively human manufacture and very much to our credit.

I am too much of a sceptic to deny the possibility of anything...

... our "Physick" and "Anatomy" have embraced such infinite varieties of being, have laid open such new worlds in time and space, have grappled, not unsuccessfully, with such complex problems, that the eyes of Vesalius and of Harvey might be dazzled by the sight of the tree that has grown out of their grain of mustard seed.