Nothing great in science has ever been done by men, whatever their powers, in whom the divine afflatus of the truth-seeker was wanting.

It is not who is right, but what is right, that is of importance.

The only question which any wise man can ask himself, and which any honest man will ask himself, is whether a doctrine is true or false.

If there is anything in the world which I do firmly believe in, it is the universal validity of the law of causation.

Follow humbly wherever and to whatever abyss Nature leads, or you shall learn nothing.

It is the first duty of a hypothesis to be intelligible.

It does not matter how many tumbles you have in this life, so long as you do not get dirty when you tumble; it is only the people who have to stop to be washed and made clean, who must necessarily lose the race. And I can assure you that there is the greatest practical benefit in making a few failures early in life. You learn that which is of inestimable importance