"Human nature has nevertheless been changed by the ever new appearance of these teachers of the purpose of existence: It now has one additional need-the need for the ever new appearance of such teachers and teachings of a "purpose. Gradually, man has become a fantastic animal that has to fulfill one more condition of existence than any other animal: man has to believe, to know, from time to time why he exists; his race cannot flourish without a periodic trust in life-without faith in reason in life."