At the age of thirty, Zarathustra goes into the wilderness and so enjoys his spirit and his solitude there that he stays for ten years. Finally, he decides to return among people, and share with them his over-brimming wisdom. Like the setting sun, he must descend from the mountain and "go under."
On his way, he encounters a saint living alone in the forest. This saint once loved mankind, but grew sick of their imperfections and now loves only God. He tells Zarathustra that mankind doesn't need the gift he brings, but rather help: they need someone to lighten their load and give them alms. Taking his leave of the saint, Zarathustra registers with surprise that the old man has not heard that "God is dead!"
Upon arriving in the town, Zarathustra begins to preach, proclaiming the overman. Man is a rope between beast and overman and must be overcome. The way across is dangerous, but it must not be abandoned for otherworldly hopes. Zarathustra urges the people to remain faithful to this world and this life, and to feel contempt for their all-too-human happiness, reason, virtue, justice, and pity. All this will prepare the way for the overman, who will be the meaning of the earth.
On hearing this, the people laugh at Zarathustra. Zarathustra suggests that while it is still possible to breed the overman, humanity is becoming increasingly tame and domesticated, and will soon be able to breed only the last man. The last men will be all alike, like herd animals, enjoying simple pleasures and mediocrity, afraid of anything too dangerous or extreme. Zarathustra says, "'We have invented happiness,' say the last men, and they blink." The people cheer, and ask Zarathustra to turn them into these last men.
Just then, a tightrope walker begins walking between two towers in the town. A jester comes out behind him, following him, and mocking him for being so awkward and moving so slowly. Suddenly, the jester jumps right over the tightrope walker, upsetting him and making him fall to the ground. Zarathustra approaches the dying man, and allays his fear of damnation by explaining that there is no devil and no hell. But then, the tightrope walker suggests that his life has been meaningless and that he has been a mere beast. Not at all, Zarathustra suggests to the dying man: "You have made danger your vocation; there is nothing contemptible in that."
That night, Zarathustra leaves town with the dead tightrope walker to bury him in the countryside. A poor day of fishing, he muses metaphorically: he has caught no men, but only a corpse. On his way out, the jester approaches him and warns him to leave. The jester says that Zarathustra is disliked here by the good and the just, and by the believers in the true faith. Only because Zarathustra isn't taken seriously is he allowed to live.
Outside the city, Zarathustra encounters a hermit, who insists on feeding both him and the corpse. After that, Zarathustra goes to sleep. He reawakens with the conviction that he must give up preaching to the masses, and seek out like- minded companions to join him. Rather than be a shepherd, who leads the herd, he must lure people away from the herd. The good and the just, and the believers in the true faith will hate him even more for this, for he will appear to be a lawbreaker and a breaker of the table of values. However, Zarathustra believes this breaking of laws and values will be a glorious act of creation.
This prologue contains the two moments in Nietzsche's writings that loom largest in popular consciousness: the declaration of the death of God and the declaration of the overman. Nietzsche first wrote "God is dead" in section 108 of The Gay Science, the book immediately preceding Zarathustra. People often mistake this phrase for the metaphysical assertion that God does not exist. In fact, Nietzsche is making the cultural observation that our idea of God is no longer strong enough to serve as the foundation for truth and morality. He is not saying that God does not exist, but that God is no longer universally accepted as giving meaning to our lives. If God was what previously gave meaning to our lives, a world without God is meaningless. Nietzsche believes his age is characterized by nihilism, lacking strong, positive goals.
The portrait of the "last man" is meant to give us the ultimate result of nihilism. Lacking any positive beliefs or needs, people will aim for comfort and to struggle as little as possible. Soon we will all become the same—all mediocre, and all perfectly content. We will "invent happiness" by eliminating every source of worry and strife from our lives.
The overman is meant to be the solution to nihilism, the meaning we should give to our lives. The German word Ubermensch is often translated as "superman," but Kaufmann's choice of "overman" is more accurate, as it brings out the way that this word evokes "overcoming" and "going under." The overman faces a world without God, and rather than finding it meaningless, gives it his own meaning. In so doing, he upsets the "good and just" and the "believers in the true faith" who have not yet come to recognize the bankruptcy of the idea of God. Essentially, the difference between regular humans and the overman is that we need to put our faith in something—be it God or science or truth—while the overman puts all his faith in himself and relies on nothing else.
Zarathustra suggests that humans are great only as a bridge between animal and overman. Humans are not the be all and end all of existence, as the "last men" would see themselves. We are still largely governed by our animal instincts, which lead us to prejudice, superficiality, and to easy reliance upon faith. In order to refine our being, we must turn our instinct for cruelty upon ourselves, and carve away at our prejudices, superficiality, and faith, creating something deeper. Zarathustra speaks of the triumphant moment where we look with contempt upon all the human qualities that we once valued. This would signify our triumph over our shallow, human nature, and our progress toward the overman.
This image of humanity as a bridge is illustrated in the story of the tightrope walker. The tightrope walker is making the slow and dangerous progress between animal and overman. The jester bears some resemblance to Zarathustra: he can move lightly (lightness and dancing are praised a great deal later in the book) and he can easily leap over those who are slower—in other words, he can cross the rope toward the overman. In urging the tightrope walker to hurry up, the jester upsets him and ruins him; similarly, Zarathustra's preaching of the overman may upset and ruin the many people who are unable to deal with this news.
Nietzsche makes many allusions in this book to the New Testament and to the ministry of Jesus. For instance, we are told that Jesus also went into the wilderness at the age of thirty, though rather than enjoying his stay there, Jesus spent forty days and forty nights in the forest being tempted and tormented by the devil. Nietzsche implicitly suggests that Jesus lacked the strength of will to enjoy his solitude, and could endure his loneliness for only just over a month. We also find echoes of the New Testament in Zarathustra's musings that he has been unsuccessful in "fishing" for followers. Jesus told his apostles that they would be fishers for men. Moreover, unlike Jesus, Zarathustra explicitly says that he does not want to be a shepherd and lead a flock of sheep: rather, he wants to teach the individual to break free from the flock.