Eternal return (also known as "eternal recurrence") is a concept which posits that time is circular, and that all history very literally repeats itself. In other words, the dinosaurs have lived an infinite number of times in the past, and they will live an infinite number of times in the future.
Likewise, the assassination of Julius Caesar has happened an infinite number of times already, and it will happen an infinite number of times in the future.
The basic premise is that the universe is limited in extent and contains a finite amount of matter, while time is viewed as being infinite. Since the number of possible changes is finite, sooner or later the same state will recur--must recur.
The concept of cyclical patterns is very prominent in Indian religions, including Hinduism and Buddhism among others. The Wheel of life represents an endless cycle of birth, life, and death from which one seeks liberation. In Tantric Buddhism, a wheel of time concept known as the Kalachakra expresses the idea of an endless cycle of existence and knowledge.
In ancient Egypt, the scarab (or dung beetle) was viewed as a sign of eternal renewal and reemergence of life, a reminder of the life to come. (See also "Atum" and "Ma'at.")
The ancient Mayans and Aztecs also took a cyclical view of time.
In ancient Greece, the concept of eternal return was connected with Empedocles, Zeno of Citium, and Stoicism.
The thought of eternal recurrence is central to the writings of Friedrich Nietzsche.
The thought of eternal recurrence appears in a few parts of his works, in particular The Gay Science and then in Thus Spoke Zarathustra.
In Ecce Homo (1888), he wrote that the thought of the Eternal Return was the "fundamental conception" of Thus Spoke Zarathustra
Nietzsche calls the idea "horrifying and paralyzing," and says that its burden is the "heaviest weight" ("das schwerste Gewicht") imaginable. The wish for the eternal return of all events would mark the ultimate affirmation of life:
- What, if some day or night a demon were to steal after you into your loneliest loneliness and say to you: 'This life as you now live it and have lived it, you will have to live once more and innumerable times more' ... Would you not throw yourself down and gnash your teeth and curse the demon who spoke thus? Or have you once experienced a tremendous moment when you would have answered him: 'You are a god and never have I heard anything more divine.' [The Gay Science, §341]
- Hatab, Lawrence J. (2005). Nietzsche's Life Sentence: Coming to Terms with Eternal Recurrence. New York : Routledge, ISBN 0-415-96758-9.
- Lorenzen, Michael. (2006). The Ideal Academic Library as Envisioned through Nietzsche’s Vision of the Eternal Return. MLA Forum 5, no. 1, online at http://www.mlaforum.org/volumeV/issue1/article3.html.
- Lukacher, Ned. (1998). Time-Fetishes: The Secret History of Eternal Recurrence. Durham, N.C. : Duke University Press, ISBN 0-8223-2253-6.
- Magnus, Bernd. (1978). Nietzsche's Existential Imperative. Bloomington : Indiana University Press, ISBN 0-253-34062-4.
- Jung, Carl. (1988). Nietzsche's Zarathustra: Notes of the Seminar Given in 1934 - 1939 (2 Volume Set). Princeton University Press, ISBN 978-0691099538.