(Doctrine of Eternal Recurrence — Preface, aph. 4)

Enlightened by an insight into the ultimate eschatological possibilities of the world we inhabit—that it is probably limited, rather than unlimited, in its possibilities—the author of this book came to realize that the very concept of the infinite, alongside that of God the Creator, may be one of our greatest inventions, devised in order for us to survive. What if infinity exists only within our experience of space and time—as Kant taught us, with unrelenting clarity—and not in the reality that surrounds us? And since our mathematics, too, historically emerged from this very experience of space and time, it is there as well that we encounter infinity, at least at its present stage of development.

On the other hand, we find that science is becoming ever less certain about what this world is (whether a universe, or perhaps a multiverse, if such a notion is indeed “to the point”), while becoming ever more certain about how it functions. Science cannot tell us what things are in themselves, nor what we ourselves are in ourselves; it cannot determine where we and things begin, and where we end—quantum mechanics, in an interpretative sense, offers only vague notions here—but it can show us how we function, and how this world, the universe (or multiverse), functions. It is precisely in this capacity to uncover the mode of functioning of all that is that, in the view of the author of these lines, the ultimate knowledge attainable by science itself resides: the discovery that this world functions as Eternal Return.

Eternal Return is, in principle, a scientifically testable hypothesis concerning the mode of functioning of all that is. After all, did not our Teacher himself describe the Doctrine of Eternal Return as precisely such a hypothesis—and, moreover, as “the most scientific” of all?!

“It is the most scientific of all possible hypotheses. We deny final purposes: if existence had one, it would have been reached already. One then understands that the circle of recurrence has no “goal,” nor anything resembling one; rather, in its entirety, it is the highest state one can conceive.” (Nachlass 1881, fragment 11[141])

Although at present this hypothesis does not seem capable of confirmation—whether because of the entropic principle of the second law of thermodynamics, or the currently most persuasive, yet still hypothetical, theory of the Big Bang, as well as quantum theory (which, in an important sense, stands in its way), and the eternally unfalsifiable metaphysical presupposition of God’s existence—this nevertheless does not mean that one day it could not become so.