Eternal return

Eternal return (or eternal recurrence) is a philosophical concept which states that time repeats itself in an infinite loop, and that exactly the same events will continue to occur in exactly the same way, over and over again, for eternity. In ancient Greece, the concept of eternal return was most prominently associated with Stoicism, the school of philosophy founded by Zeno of Citium. The Stoics believed that the universe is periodically destroyed and reborn, and that each universe is exactly the same as the one before. This doctrine was fiercely refuted by Christian authors such as Augustine, who saw in it a fundamental denial of free will and of the possibility of salvation. The global spread of Christianity therefore brought an end to classical theories of eternal return. The concept was revived in the 19th century by German philosopher Friedrich Nietzsche. Having briefly presented the idea as a thought experiment in The Gay Science, he explored it more thoroughly in his novel Thus Spoke Zarathustra, in which the protagonist learns to overcome his horror of the thought of eternal return. It is not known whether Nietzsche believed in the literal truth of eternal return, or, if he did not, what he intended to demonstrate by it. Nietzsche's ideas were subsequently taken up and re-interpreted by other writers, such as Russian esotericist P. D. Ouspensky, who argued that it was possible to break the cycle of return. There are hints in ancient writings that the theory of eternal return may have originated with Pythagoras (c. 570 – c. 495 BC). According to Porphyry, it was one of the teachings of Pythagoras that "after certain specified periods, the same events occur again" and that "nothing was entirely new". Eudemus of Rhodes also references this Pythagorean doctrine in his commentary on Aristotle's Physics. In a fragment preserved by Simplicius, Eudemus writes: One might raise the problem whether the same time recurs, as some say, or not.