The principle of contradiction establishes merely the agreement of concepts, but does not itself produce concepts.

The discovery of truth is prevented more effectively, not by the false appearance things present and which mislead into error, not directly by weakness of the reasoning powers, but by preconceived opinion, by prejudice.

Every original idea is first ridiculed, then vigorously attacked, and finally taken for granted.

On the path of actions, great heart is the chief recommendation; on that works, a great head.

That a god like Jehovah should have created this world of misery and woe, out of pure caprice, and because he enjoyed doing it, and should then have clapped his hands in praise of his own work, and declared everything to be very good-that will not do at all!

The man who goes up in a balloon does not feel as if he were ascending; he only sees the earth sinking deeper below him.

Reasonable and vicious are quite consistent with each other, in fact, only through their union are great and far-reaching crimes possible