I am often surprised by the cleverness, and now and again by the stupidity, of my dog; and I have similar experiences with mankind.

Animals hear about death for the first time when they die.

A man's knowledge may be said to be mature, in other words, when it has reached the most complete state of perfection to which he, as an individual, is capable of bringing it, when an exact correspondence is established between the whole of his abstract ideas and the things he has actually perceived for himself. His will mean that each of his abstract ideas rests, directly or indirectly, upon a basis of observation, which alone endows it with any real value; and also that he is able to place every observation he makes under the right abstract idea which belongs to it.

The principle of contradiction establishes merely the agreement of concepts, but does not itself produce concepts.

Monotheistic religions alone furnish the spectacle of religious wars, religious persecutions, heretical tribunals, that breaking of idols and destruction of images of the gods, that razing of Indian temples and Egyptian colossi, which had looked on the sun 3,000 years: just because a jealous god had said, Thou shalt make no graven image.

Wealth is like sea-water; the more we drink, the thirstier we become; and the same is true of fame.

The truth can wait, for it lives a long life.