In Deleuze's reading, then, the eternal recurrence does not imply the recurrence of fixed states of being, like the lining up of marks on wheels. It is precisely the being of such states that Deleuze wants to deny. In a universe of constant becoming, the notion of being is replaced by the notion of returning, or recurrence: "Returning is the being of that which becomes," Deleuze writes. Thus, in Nietzsche's conception of the universe, there are no fixed things, like a one true God or one fixed morality or the like. All things change, but these changes recur eternally.
The eternal recurrence is mostly significant to Nietzsche in how we might confront the fact of recurrence. We would have to abandon the notions that there is some reason or purpose driving the universe, and accept the fact that chance governs these changes as much as anything else. We would also have to accept that everything we have done and everything that we will do will be repeated an infinite number of times. While it might seem delightful that our happiest moments might be repeated infinitely, we must also confront the fact that our worst moments and our mediocrity must always be repeated and never improved upon. Zarathustra cannot confront the thought of eternal recurrence, largely because he would have to recognize that the mediocrity of humanity that he so despises will never be fully overcome, but rather will be repeated over and over again.