
Aion (fromHellenistic Greek:αἰών,romanized: aión,lit. 'long period of time',[ai̯ˈɔːn]) is aHellenistic deity associated with time, the orb or circle encompassing the universe, and thezodiac.The "time" which Aion represents isperpetual, unbounded, ritual, and cyclic: The future is a returning version of the past, later calledaevum (seeVedic SanskritṚtú). Philosophically and mythologically, especially in the context of the mysteries, Aion is understood as the ontological personification ofeternity : the time of indestructible permanence,[2][3] which is in essence the duration of the fact of Existence, understood as eternal and immutable.[4]
This kind of time contrasts withempirical, linear, progressive, and historical time thatChronos represented, which divides into past, present, and future.[5]: 274
Aion is thus a god of the cyclic ages, and thecycle of the year and thezodiac. In the latter part of theClassical era he became associated withmystery religions concerned with theafterlife, such as the mysteries ofCybele, theDionysian mysteries,Orphic religion, and theMithraic mysteries. InLatin, the concept of the deity may appear asAeternitas,Anna Perenna, orSaeculum.[5]: 274 He is typically in the company of an earth ormother goddess such asTellus orCybele, as on theParabiago plate.[5]: 274
Aion is usually identified as the nude or mostly nude young man within a circle representing thezodiac, symbolic of eternal andcyclical time. Examples include two Roman mosaics fromSentinum (modern–daySassoferrato) andHippo Regius inRoman Africa, and theParabiago plate. But because he represents time as a cycle, he may also be presented as an old man. In theDionysiaca,Nonnus associates Aion with theHorae and says that he:
The imagery of the twining serpent is connected to the hoop or wheel through theouroboros, a ring formed by a snake holding the tip of its tail in its mouth. The 4th century CE Latin commentatorServius notes that the image of a snake biting its tail represents the cyclical nature of the year.[8]

In his 5th century work onhieroglyphics,Horapollo makes a further distinction between a serpent that hides its tail under the rest of its body, which represents Aion, and the ouroboros that represents thekosmos, which is the serpent devouring its tail.[9]
Martianus Capella (5th century CE) identified Aion withCronus (LatinSaturnus), whose name caused him to be theologically conflated with Chronos ("Time"), in the way that the Greek ruler of the underworld Plouton (Pluto) was conflated with Ploutos (Plutus, "Wealth"). Martianus presents Cronus-Aion as the consort ofRhea (LatinOps) as identified withPhysis.[7]: 137
In his highly speculative reconstruction ofMithraic cosmogony,Franz Cumont positioned Aion as Unlimited Time (sometimes represented asSaeculum, Cronus, or Saturn) as the god who emerged from primordialChaos, and who in turn generated Heaven and Earth. Modern scholars call this deity the'leonto‑cephaline' figure – a winged, lion-headed, nude male, whose torso is entwined by a serpent. He typically holds a sceptre, keys, and / or a thunderbolt. Nobody knows for surewho he was or what he represented, but aside from the lion-head, depictions of him have Aion's icons; in rare instances, his statue appears inmithrea with the human head, and with the lion-head gone, he is indistinguishable from Aion.[10]: 78
Aion is identified withDionysus in Christian and Neoplatonic writers, but there are no references to Dionysus as Aion before theChristian era.[11]Euripides, however, does call Aion a 'son ofZeus'.[12]
TheSuda identifies Aion withOsiris andAdonis (probably because originally Adonis had been a god who was later downgraded to the status of "mortal" since he was believed to have died). InPtolemaic Alexandria, at the site of a dream oracle, the Hellenisticsyncretic godSerapis was identified as Aion Plutonius.[14][15] The epithetPlutonius marks functional aspects shared with Pluto, consort ofPersephone and ruler of the underworld in theEleusinian tradition.Epiphanius says that at Alexandria Aion's birth fromKore the Virgin was celebrated6 January:[13]: 306–307 "On this day and at this hour the Virgin gave birth to Aion." The date, which coincides withEpiphany, brought new year's celebrations to a close, completing the cycle of time that Aion embodies.[16]
The Alexandrian Aion may be a form of Osiris-Dionysus, reborn annually;[13]: 309 his image was marked with crosses on his hands, knees, and forehead.[13]: 306–307, 311 Quispel (2008) conjectured that the figure resulted from integrating theOrphicPhanes, who like Aion is associated with a coiling serpent, intoMithraic religion at Alexandria, and that he "assures the eternity of the city."[17]: 258
In the art of the Roman era, Aion was often conflated with the primordial sky godUranus /Caelus.[citation needed]
This syncretic Aion became a symbol and guarantor of the perpetuity ofRoman rule, and emperors such asAntoninus Pius issued coins with the legendAion,[13]: 314 whose (female) Roman counterpart wasAeternitas.[18] Roman coins associate both Aion andAeternitas with thephoenix as a symbol of rebirth and cyclical renewal.[5]: 307–308
Aion was among the virtues and divine personifications that were part of lateHellenic discourse, in which they figure as "creative agents in grand cosmological schemes".[19] The significance of Aion lies in his malleability: He is a "fluid conception" through which various ideas about time and divinity converge in the Hellenistic era, in the context of syncretic andmonotheistic tendencies.[5]: 307–308 ff
according to the Egyptians, before the invention of the alphabet, the year was symbolized by a picture of a serpent biting its own tail, because it recurs on itself" (annus secundum Aegyptios indicabatur ante inventas litteras picto dracone caudam suam mordente, quia in se recurrit)cited byShanzer (1986)[7]: 154