Liberty is the breath of progress.

Any doctrine that will not bear investigation is not a fit tenant for the mind of an honest man.

Christianity has such a contemptible opinion of human nature that it does not believe a man can tell the truth unless frightened by a belief in god. No lower opinion of the human race has ever been expressed.

One good schoolmaster is worth a thousand priests.

The way to be happy is to make others so.

I would have all the professors in colleges, all the teachers in schools of every kind, including those in Sunday schools, agree that they would teach only what they know, that they would not palm off guesses as demonstrated truths.

The closer I'm bound in love to you, the closer I am to free.