Escape from boredom is one of the really powerful desires of almost all human beings.

Mathematics rightly viewed possesses not only truth but supreme beauty.

The wise man thinks about his troubles only when there is some purpose in doing so; at other times he thinks about other things, or, if it is night, about nothing at all.

A man who has once perceived, however temporarily and however briefly, what makes greatness of soul, can no longer be happy if he allows himself to be petty, self-seeking, troubled by trivial misfortunes, dreading what fate may have in store for him. The man capable of greatness of soul will open wide the windows of his mind, letting the winds blow freely upon it from every portion of the universe.

The desire to understand the world and the desire to reform it are the two great engines of progress, without which human society would stand still or retrogress.

Meantime, the world in which we exist has other aims. But it will pass away, burnt up in the fire of its own hot passions; and from its ashes will spring a new and younger world, full of fresh hope, woth the light of morning in its eyes.

In the first place a philosophical proposition must be general. It must not deal specially with things on the surface of the earth, or within the solar system, or with any other portion of space and time. . . . This brings us to a second characteristic of philosophical propositions, namely that they must be a priori. A philosophical proposition must be such as can neither be proved nor disproved by empirical evidence. . . . Philosophy, if what has been said is correct, becomes indistinguishable from logic as that word has now come to be used.