The brain may be regarded as a kind of parasite of the organism, a pensioner, as it were, who dwells with the body.

What a torture to talk to filled heads that allow nothing from the outside to enter them.

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

Sooner or later if the activity of the mind is restricted anywhere, it will cease to function even where it is allowed to be free.

To be too conscious is an illness—a real thoroughgoing illness.

Every thought is, strictly speaking, an afterthought.

The highest possible stage in moral culture is when we recognize that we ought to control our thoughts.

The mind is not, I know, a highway but a temple, and its doors should not be carelessly left open.

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

Imagination continually outruns the creature it inhabits.

Though this be madness, yet there is method in’t.

The most potent weapon in the hands of the oppressor is the mind of the oppressed.

What is the hardest task in the world? To think.