Eternal Return
The idea that the universe and everything in it has occurred and will recur in exactly the same way an infinite number of times, with every moment repeating in an endless cycle.
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Origin
Cyclical cosmologies appear in ancient Hindu, Buddhist, and Stoic thought, but Friedrich Nietzsche reframed the idea as a philosophical thought experiment. He first presented it in The Gay Science (1882, section 341) and made it the central concept of Thus Spoke Zarathustra (1883–1885). Nietzsche said the idea struck him in August 1881 while walking near Lake Silvaplana in the Swiss Alps.
Updated February 22, 2026