“I think, therefore I am” is the statement of an intellectual who underrates toothaches.

The real question is not whether machines think but whether men do.

Brains are the only things worth having in this world.

Strength of mind is exercise, not rest.

Madness need not be all breakdown. It may also be breakthrough.

In psychoanalysis nothing is true except the exaggerations.

A mind lively and at ease can do with seeing nothing, and can see nothing that does not answer.

Every thought is, strictly speaking, an afterthought.

Don’t lose your mind unless you have paid for it.

The human mind is an evolutionary product, just like the human body.

It is far, far better and much safer to have a firm anchor in nonsense than to put out on the troubled seas of thought.

Imagination is the secret and marrow of civilization. It is the very eye of faith.

Understanding is a very dull occupation.