God is a word to express, not our ideas, but the want of them.

If two or more instances of the phenomenon under investigation have only one circumstance in common, the circumstance in which alone all the instances agree is the cause (or effect) of the given phenomenon.

A man of clear ideas errs grievously if he imagines that whatever is seen confusedly does not exist; it belongs to him, when he meets with such a thing, to dispel the midst, and fix the outlines of the vague form which is looming through it.

Whatever helps to shape the human being - to make the individual what he is, or hinder him from being what he is not - is part of his education.

Belief, thus, in the supernatural, great as are the services which it rendered in the early stages of human development, cannot be considered to be any longer required, either for enabling us to know what is right and wrong in social morality, or for supplying us with motives to do right and to abstain from wrong.

The duty of man is the same in respect to his own nature as in respect to the nature of all other things, namely not to follow it but to amend it.

Eloquence is heard; poetry is overheard ... All poetry is of the nature of the soliloquy.