Virtue is as little to be acquired by learning as genius; nay, the idea is barren, and is only to be employed as an instrument, in the same way as genius in respect to art. It would be as foolish to expect that our moral and ethical systems would turn out virtuous, noble, and holy beings, as that our aesthetic systems would produce poets, painters, and musicians.

Politeness is to human nature what warmth is to wax.

Philosophy ... is a science, and as such has no articles of faith; accordingly, in it nothing can be assumed as existing except what is either positively given empirically, or demonstrated through indubitable conclusions.

It is most important to allow the brain the full measure of sleep which is required to restore it; for sleep is to a man's whole nature what winding up is to a clock.

Virtue is as little to be acquired by learning as genius; nay, the idea is barren, and is only to be employed as an instrument, in the same way as genius in respect to art. It would be as foolish to expect that our moral and ethical systems would turn out virtuous, noble, and holy beings, as that our aesthetic systems would produce poets, painters, and musicians.

Not to go to the theater is like making one's toilet without a mirror.

Every man takes the limits of his own field of vision for the limits of the world. This is an error of the intellect as inevitable as that error of the eye which lets you fancy that on the horizon heaven and earth meet.