Eternity
Eternity, also referred to as sempiternity or forever, is time with no end i.e. infinite.
In the context of human life, eternity and death are co-existing realities.
Philosophy
Plato described time as the moving image of eternity in Timaeus using the word: αἰών. Aristotle stated οὐρανοῦ was eternal and an eternal world.The ancient Greek word for everlastingness was ἀίδιος as exists via Plotinus, who also used the word aoin , in Ennead III.7. The thought of Classical period Augustine, as exists in Book XI of the Confessions, and Boethius, in Book V of the Consolation of Philosophy were adopted as the reality of the subject for later thinkers in the western tradition of philosophy.
Thomas Hobbes and many others in the Age of Enlightenment drew on the classical distinction to put forward metaphysical hypotheses such as "eternity is a permanent now".
Religion
Ancient Egyptian eternity terms were neheh, for cyclical time, and djet, for linear. Rameses III funerary temple was: 'United-with -Eternity'In Genesis 21:33 of the Old Testament El-Olam is God-Eternal.
Mythic Iliadical ἀθάνατος is the immortal.
Eternity as infinite duration is an important concept in many lives and religions. God or gods are often said to endure eternally, or exist for all time, forever, without beginning or end. Religious views of an afterlife may speak of it in terms of eternity or eternal life. Christian theologians may regard immutability, like the eternal Platonic forms, as essential to eternity.
The ancient greek word for everlasting and, or, eternal exists in the Orphica Hymni.
Boethius stated eternity was: interminabilis vitae tota simul et perfecta possessio, which is translated as "simultaneously full and perfect possession of interminable life". and nunc permanens, which in English is a: permanent now. Thomas Aquinas believed in an eternal God, without either a beginning or end; the concept of eternity is of divine simplicity, thus incapable of being defined or fully understood by humankind.