Eternity

Eternity in common parlance is either an infinite or an indeterminately long period of time. In classical philosophy, however, eternity is defined as what exists outside time while sempiternity is the concept that corresponds to the colloquial definition of eternity.

Eternity is an important concept in many religions, where the God or the gods are said to endure eternally. Some, such as Aristotle, would say the same about the natural cosmos in regard to both past and future eternal duration, and like the eternal Platonic forms, immutability was considered essential.

Aristotle argued that the cosmos has no beginning. In Aristotle's metaphysics, eternity is the unmoved mover (God), understood as the gradient of total synergy ("produces motion by being loved").Boethius defined eternity as "simultaneously full and perfect possession of interminable life".

Eternity is often symbolized by the image of a snake swallowing its own tail, known as the Ouroboros (or Uroboros). The circle is also commonly used as a symbol for eternity, as is the mathematical symbol of infinity, ${\displaystyle \infty }$.

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