The extraordinary courage and wisdom of Kant and Schopenhauer have succeeded in gaining the most difficult victory, the victory over the optimism concealed in the essence of logic-an optimism that is the basis of our culture.

The true logic of this world is in the calculus of probabilities.

For nothing is more democratic than logic; it is no respecter of persons and makes no distinction between crooked and straight noses.

Fear is the enemy of logic.

Believe nothing, no matter where you read it, or who said it, no matter if I have said it, unless it agrees with your own reason and your own common sense.

There is no place in a fanatic's head where reason can enter.