The presence of Schopenhauer in “Thus Spoke Zarathustra”: by the way of a letter

The purpose of this essay is to show that although Nietzsche announced, in a letter of August 1882, after the end of Book IV of the GC, which may never return to Schopenhauer, in his later work, ZA, he elects, the prophet of compassion, as the arch enemy that your protagonist will have to fight over the plot, as in last instance is the feeling of compassion that Zarathustra will have to overcome to become what he is