Mathematics is only the art of saying the same thing in different words.

When we look at a rock what we are seeing is not the rock, but the effect of the rock upon us.

The wise use of leisure, it must be conceded, is a product of civilization and education.

One eminently orthodox Catholic divine laid it down that a confessor may fondle a nun's breasts, provided he does it without evil intent.

One of the chief triumphs of modern mathematics consists in having discovered what mathematics really is.

All forms of fear produce fatigue.

Almost everything that distinguishes the modern world from earlier centuries is attributable to science, which achieved its most spectacular triumphs in the seventeenth century.