Thus Spake Zarathustra: A Book for All and None by Friedrich Wilhelm Nietzsche

This refers, of course, to Schopenhauer. Nietzsche, as is well known, was at one time an ardent follower of Schopenhauer. He overcame Pessimism by discovering an object in existence; he saw the possibility of raising society to a higher level and preached the profoundest Optimism in consequence.