We do not really think, we are barely conscious, until something goes wrong.

Still, it will sometimes strike a scientific man that the philosophers have been less intent on finding out what the facts are, than on inquiring what belief is most in harmony with their system.

Theoretically, I grant you, there is no possibility of error in necessary reasoning. But to speak thus "theoretically," is to uselanguage in a Pickwickian sense. In practice, and in fact, mathematics is not exempt from that liability to error that affects everything that man does.

It is... easy to be certain. One has only to be sufficiently vague.

Looking out of my window this lovely spring morning I see an azalea in full bloom. No, no! I do not see that; though that is the only way I can describe what I see. That is a proposition, a sentence, a fact; but what I perceive is not proposition, sentence, fact, but only an image which I make intelligible in part by means of a statement of fact. This statement is abstract; but what I see is concrete.

We, one and all of us, have an instinct to pray; and this fact constitutes an invitation from God to pray.

This branch of mathematics [Probability] is the only one, I believe, in which good writers frequently get results which are entirely erroneous.