Truly speaking, it is not instruction, but provocation, that I can receive from another soul. What he announces, I must find true in me, or reject; and on his word, or as his second, be he who he may, I can accept nothing.

Every fact is related on one side to sensation, and, on the other, to morals. The game of thought is, on the appearance of one of these two sides, to find the other: given the upper, to find the under side.

It makes a great difference in the force of a sentence, whether a man be behind it or no.

Crossing a bare common, in snow puddles at twilight, under a clouded sky, without having in my thoughts any occurrence of special good fortune, I have enjoyed perfect exhilaration. I am glad to the brink of fear.

The poisons are our principal medicines, which kill the disease and save the life.

All necessary truth is its own evidence.

If, at any time, it comes into my head, that a present is due from me to somebody, I am puzzled what to give, until the opportunity is gone.