The Eternal Recurrence, also known as Eternal Circle, is a system that brings the universe to a "reset" point in the past when either Anima is on the verge of activating or the Collective Unconscious is on the verge of collapsing.
When the system is invoked, every consciousness forgets its past life. Thus humanity and all life lives in an eternal cycle - the Lower Domain is reset through the big bang and life is trapped in an endless cycle, repeating itself from the big bang and to the future onwards until the next inevitable Eternal Recurrence.
Wilhelm and Eternal Recurrence
Wilhelm, the Guardian of the Lower Domain, has succeeded many times in activating the recurrence in previous universes, but each recurrence differs because U-DO is unaffected by the recurrence and its consciousness continues to evolve. Wilhelm, too, at the same time that Eternal Recurrence is achieved, forgets everything, and he intends to plan Eternal Recurrence to save the universe.
Rejection of the Eternal Recurrence
It is implied that, after every Eternal Recurrence, humanity subconsciously begins to reject the Eternal Recurrence due to some sort of after effect, and this subconscious desire reflects in humanity's actions.
In Xenosaga Episode III: Also sprach Zarathustra, Eternal Recurrence is prevented. Wilhelm is disappointed because he claims that the collapse of the universe is imminent someday. It is suggested that the universe will last another few tens of thousands of years before it perishes, and that the answer to prevent this lies at Lost Jerusalem.
Necessary factors to activate Zarathustra for the Eternal Recurrence
- Mary Magdalene (Animus)
- The Maiden of Mary's will (Shion Uzuki)
- Shion's pendant (Zarathustra's ignition key)
- The original Zohar (and possibly Lemegeton to use it)
- 12 Vessels of Anima
- Joshua - On Michtam, Wilhelm sealed away Abel's power using Joshua. The 'two Abel', or eyes of God, as Wilhelm calls Abel and Abel's Ark, needed to be sealed away. To perform Eternal Recurrence, Wilhelm needed to prevent U-DO's observation of the universe.)