All knowledge is good. It is impossible to say any fragment of knowledge, however insignificant or remote from one's ordinary pursuits, may not some day be turned to account.

For myself I say deliberately, it is better to have a millstone tied round the neck and be thrown into the sea than to share the enterprises of those to whom the world has turned, and will turn, because they minister to its weaknesses and cover up the awful realities which it shudders to look at.

There is but one right, and the possibilities of wrong are infinite.

What are the moral convictions most fondly held by barbarous and semi-barbarous people? They are the convictions that authority is the soundest basis of belief; that merit attaches to readiness to believe; that the doubting disposition is a bad one, and skepticism is a sin.

The question of all questions for humanity, the problem which lies behind all others and is more interesting than any of them, is that of the determination of man's place in nature and his relation to the cosmos.

Time, whose tooth gnaws away everything else, is powerless against truth.

Not only does every animal live at the expense of some other animal or plant, but the very plants are at war.... The individuals of a species are like the crew of a foundered ship, and none but good swimmers have a chance of reaching the land.