Only one absolute certainty is possible to man, namely that at any given moment the feeling which he has exists.

Teach a man to read and write, and you have put into his hands the great keys of the wisdom-box.

Every philosophical thinker hails it [The Origin of Species] as a veritable Whitworth gun in the armoury of liberalism.

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.

Perhaps the most valuable result of all education is the ability to make yourself do the thing you have to do, when it ought to be done, whether you like it or not. It is the first lesson that ought to be learned and however early a man's training begins, it is probably the last lesson that he learns thoroughly.

History warns us that it is the customary fate of new truths to begin as heresies and to end as superstitions.

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