It is hard to overstate the debt we owe to the men and women of genius.

Every creed is a rock in running water: humanity sweeps by it. Every creed cries to the universe, "Halt!" A creed is the ignorant Past bulling the enlightened Present.

The history of intellectual progress is written in the lives of infidels.

Reason, observation, and experience; the holy trinity of science.

We need men with moral courage to speak and write their real thoughts, and to stand by their convictions, even to the very death.

I would rather live with the woman I love in a world full of trouble, than to live in heaven with nobody but men.

There will never be a generation of great men until there has been a generation of free women - of free mothers.