Proof is an idol before whom the pure mathematician tortures himself. – Arthur Stanley Eddington, The Nature of the Physical World

Nature does not count nor do integers occur in nature. Man made them all, integers and all the rest, Kronecker to the contrary notwithstanding. – Percy William Bridgman, The Way Things Are

Arithmetic is where numbers fly like pigeons in and out of your head. – Carl Sandburg, "Arithmetic"

Although I am almost illiterate mathematically, I grasped very early in life that any one who can count to ten can count upward indefinitely if he is fool enough to do so. – Robertson Davies, "Of the Conservation of Youth," The Table Talk of Samu