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.

No great achievement is possible without persistent work.

It's coexistence or no existence.

The human heart as modern civilization has made it is more prone to hatred than to friendship. And it is prone to hatred because it is dissatisfied.

The mind is a strange machine which can combine the materials offered to it in the most astonishing ways.

We are all prone to the malady of the introvert who with the manifold spectacle of the world spread out before him, turns away and gazes only upon the emptiness within.

The fact that a belief has a good moral effect upon a man is no evidence whatsoever in favor of its truth. I'm not contending in a dogmatic way that there is not a God. What I'm contending is that we don't know that there is. I don't like the word "absolute." I don't think there is anything absolute whatever. The moral law, for example, is always changing. At one period in the development of the human race, almost everybody thought cannibalism was a duty.