One must be oneself very little of a philosopher not to feel that the finest privilege of our reason consists in not believing in anything by the impulsion of a blind and mechanical instinct, and that it is to dishonour reason to put it in bonds as the Chaldeans did. Man is born to think for himself.

The following general definition of an animal: a system of different organic molecules that have combined with one another, under the impulsion of a sensation similar to an obtuse and muffled sense of touch given to them by the creator of matter as a whole, until each one of them has found the most suitable position for its shape and comfort.

If reason be a gift of Heaven, and we can say as much of faith, Heaven has certainly made us two gifts not only incompatible, but in direct contradiction to each other. In order to solve the difficulty, we are compelled to say either that faith is a chimera or that reason is useless.

Only God and some few rare geniuses can keep forging ahead into novelty.

Time, matter, space - all, it may be, are no more than a point.

Which is the greater merit, to enlighten the human race, which remains forever, or to save one's fatherland, which is perishable?

If you want me to believe in God, you must make me touch him.