my mind is
a big hunk of irrevocable nothing

—E.E. Cummings, 1923

What is outside my mind means nothing to it.

—Marcus Aurelius, c. 170

Every thought is, strictly speaking, an afterthought.

—Hannah Arendt, 1978

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

—Joseph Joubert, 1807

The march of the human mind is slow.

—Edmund Burke, 1775

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

—Charles Darwin, 1871

Any man could, if he were so inclined, be the sculptor of his own brain.

—Santiago Ramón y Cajal, 1897

Brain, n. An apparatus with which we think that we think.

—Ambrose Bierce, 1906

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

—Arthur Schopenhauer, 1851

In psychoanalysis nothing is true except the exaggerations.

—Theodor Adorno, 1951

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.

—Edith Hamilton, 1930

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

—Henry Ward Beecher, 1887

Not all heads have a brain.

—French proverb