Two things strike me dumb: the infinite starry heavens, and the sense of right and wrong in man.

Freedom is the alone unoriginated birthright of man, and belongs to him by force of his humanity; and is independence on the will and co-action of every other in so far as this consists with every other person's freedom.

All our knowledge begins with the senses...

The yellow Indians do have a meagre talent. The Negroes are far below them, and at the lowest point are a part of the American people.

He who has made great moral progress ceases to pray

Fallacious and misleading arguments are most easily detected if set out in correct syllogistic form.

By a lie a man throws away and, as it were, annihilates his dignity as a man. A man who himself does not believe what he tells another ... has even less worth than if he were a mere thing. ... makes himself a mere deceptive appearance of man, not man himself.