Skepticism is the highest duty and blind faith the one unpardonable sin.

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

My reflection, when I first made myself master of the central idea of the 'Origin', was, 'How extremely stupid not to have thought of that!'

Sit down before fact as a little child, be prepared to give up every conceived notion, follow humbly wherever and whatever abysses nature leads, or you will learn nothing.

Teach a child what is wise, that is morality. Teach him what is wise and beautiful, that is religion!

The rules of the game are what we call the laws of nature.

That which endures is not one or another association of living forms, but the process of which the cosmos is the product, and of which these are among the transitory expressions.