Four thousand volumes of metaphysics will not teach us what the soul is.

Metaphysics means nothing but an unusually obstinate effort to think clearly.

The most heterogeneous ideas are yoked by violence together; nature and art are ransacked for illustrations, comparisons, and allusions; their learning instructs, and their subtlety surprises; but the reader commonly thinks his improvement dearly bought and, though he sometimes admires, is seldom pleased.

When he to whom a person speaks does not understand, and he who speaks does not understand himself, that is metaphysics.

A little cooling down of animal excitability and instinct, a little loss of animal toughness, a little irritable weakness and descent of the pain-threshold, will bring the worm at the core of all our usual springs of delight into full view, and turn us into melancholy metaphysicians.

A metaphysician is one who, when you remark that twice two makes four, demands to know what you mean by twice, what by two, what by makes, and what by four. For asking such questions metaphysicians are supported in oriental luxury in the universities, and respected as educated and intelligent men.

Two half philosophers will probably never a whole metaphysician make.

I was thrown out of N.Y.U. my freshman year for cheating on my metaphysics final. You know, I looked within the soul of the boy sitting next to me.