Theology is not what we know about God, but what we do not know about Nature.

If a man would follow, today, the teachings of the Old Testament, he would be a criminal. If he would follow strictly the teachings of the New, he would be insane.

If I go to heaven I want to take my reason with me.

Diderot took the ground that, if orthodox religion be true Christ was guilty of suicide. Having the power to defend himself he should have used it.

Progress is born of doubt and inquiry. The Church never doubts, never inquires. To doubt is heresy, to inquire is to admit that you do not know—the Church does neither.

I am simply in favor of intellectual hospitality-that is all. You come to me with a new idea. I invite you into the house. Let us see what you have. Let us talk it over. If I do not like your thought, I will bid it a polite "good day." If I do like it, I will say: "Sit down; stay with me, and become a part of the intellectual wealth of my world."

I believe that there is something far nobler than loyalty to any particular man. Loyalty to the truth as we perceive it - loyalty to our duty as we know it - loyalty to the ideals of our brain and heart - is, to my mind, far greater and far nobler than loyalty to the life of any particular man or God. . . .