Life is doubt, and faith without doubt is nothing but death.

Our life is a hope which is continually converting itself into memory and memory in its turn begets hope.

Those faults we do not have, do not bother us.

These terrible sociologists, who are the astrologers and alchemists of our twentieth century.

True science teaches, above all, to doubt and be ignorant.

Man habitually sacrifices his life to his purse, but he sacrifices his purse to his vanity.

Man is perishing. That may be, and if it is nothingness that awaits us let us so act that it will be an unjust fate.