Every church that has a standard higher than human welfare is dangerous.

I would rather that we all should go to eternal chaos, to black and starless night, than that just one soul should suffer eternal agony.

Talent has the four seasons: spring, that is to say, the sowing of the seeds; summer, growth; autumn, the harvest; winter, intellectual death. But there is now and then a genius who has no winter, and, no matter how many years he may live, on the blossom of his thought no snow falls. Genius has the climate of perpetual growth.

Who can over estimate the progress of the world if all the money wasted in superstition could be used to enlighten, elevate and civilize mankind?

The present is the necessary product of all the past, the necessary cause of all the future.

I have no confidence in any religion that can be demonstrated only to children.

I am anxious to give away information, for it is only by giving it away that you can keep it. When you have told it, you remember it. It is with information as it is with liberty, the only way to be dead sure of it is to give it to other people.