If everything has a cause, then God must have a cause. If there can be anything without a cause, it may just be the world as God.

Aristotle could have avoided the mistake of thinking that women have fewer teeth than men, by the simple device of asking Mrs. Aristotle to keep her mouth open while he counted.

But if thought is to become the possession of many, not the privilege of the few, we must have done with fear. It is fear that holds men back - fear lest their cherished beliefs should prove delusions, fear lest the institutions by which they live should prove harmful, fear lest they themselves should prove less worthy of respect than they have supposed themselves to be.

Indemnity for the past and security for the future.

One's work is never so bad as it appears on bad days, nor so good as it appears on good days.

Humanistic ethics is based on the principle that only humans themselves can determine the criterion for virtue and not an authority transcending us.

The law of causality, I believe, like much that passes muster among philosophers, is a relic of a bygone age, surviving, like the monarchy, only because it is erroneously supposed to do no harm.