In the religion of Thelema, it is believed that the history of humanity can be divided into a series of aeons, each of which was accompanied by its own forms of "magical and religious expression". The first of these was the Aeon of Isis, which Thelemites believed occurred during prehistory and which saw mankind worshipping a Great Goddess, symbolised by the ancient Egyptian deity Isis. In Thelemite beliefs, this was followed by the Aeon of Osiris, a period that took place in the classical and mediaeval centuries, when humanity worshipped a singular male god, symbolised by the Egyptian god Osiris, and was therefore dominated by patriarchal values. And finally the third aeon, the Aeon of Horus, which was controlled by the child god, symbolised by Horus. In this new aeon, Thelemites believe that humanity will enter a time of self-realization and self-actualization.
Within the Thelemite religion, each of these aeons is believed to be "characterized by their [own specific] magical formula", the use of which "is very important and fundamental to the understanding of ... Thelemic Magick".
Aeon of Isis
The first Aeon of Isis was maternal, where the female aspect of the Godhead was revered due to a mostly matriarchal society and the idea that "Mother Earth" nourished, clothed and housed man. It was characterized by pagan worship of the Mother and Nature. In his Equinox of the Gods Crowley describes this period as "simple, quiet, easy, and pleasant; the material ignores the spiritual" (Equinox of the Gods).
Lon Milo DuQuette remarked that this aeon was "the Age of the Great Goddess", and that it had originated in prehistory, reaching its zenith at "approximately 2400 B.C." Continuing with this idea, he remarked that this period was when "the cult of the Great Goddess was truly universal. She was worshipped by countless cultures under myriad names and forms. It would also be a mistake for us to conclude that the magical formula of this period manifested exclusively through the worship of any particular anthropomorphic female deity. For, like every aeon, the magical formula of the Aeon of Isis was founded upon mankind's interpretation of the 'perceived facts' of nature, and our Isian-age progenitors perceived nature as a continuous process of spontaneous growth."
Aeon of Osiris
The classical and medieval Aeon of Osiris is considered to be dominated by the paternal principle and the formula of the Dying God. This Aeon was characterized by that of self-sacrifice and submission to the Father God. Crowley says of this Aeon in his Heart of the Master:
Formula of Osiris, whose word is IAO; so that men worshiped Man, thinking him subject to Death, and his victory dependent upon Resurrection. Even so conceived they of the Sun as slain and reborn with every day, and every year.
Crowley also says of the Aeon of Osiris in Equinox of the Gods:
The second [Aeon] is of suffering and death: the spiritual strives to ignore the material. Christianity and all cognate religions worship death, glorify suffering, deify corpses.
Aeon of Horus
The modern Aeon of Horus is portrayed as a time of self-realization as well as a growing interest in all things spiritual, and is considered to be dominated by the principle of the child. The Word of its Law is Thelema (will), which is complemented by Agape (love), and its formula is Abrahadabra. Individuality and finding the individual's True Will are the dominant aspects; its formula is that of growth, in consciousness and love, toward self-realization. Concerning the Aeon of Horus, Crowley wrote:
... the crowned and conquering child, who dieth not, nor is reborn, but goeth radiant ever upon His Way. Even so goeth the Sun: for as it is now known that night is but the shadow of the Earth, so Death is but the shadow of the Body, that veileth his Light from its bearer. (Heart of the Master)
And also, in his Little Essays Toward Truth:
The Aeon of Horus is here: and its first flower may well be this: that, freed of the obsession of the doom of the Ego in Death, and of the limitation of the Mind by Reason, the best men again set out with eager eyes upon the Path of the Wise, the mountain track of the goat, and then the untrodden Ridge, that leads to the ice-gleaming pinnacles of Mastery!
Lon Milo DuQuette commented on the connection that the Aeon of Horus had to the Age of Aquarius when he stated that "Yes, [the Aeon of Horus] is coincidental to what astrologers and songwriters call the Age of Aquarius and what millions of others refer to simply as the New Age. But it would be a mistake to view this new aeon simply as another tick on a great cosmic clock. The Age of Aquarius, profoundly significant as it is, is only one aspect of a far greater new spiritual age."
Some Thelemites believe that the Aeon of Ma'at will eventually replace the present one. According to one of Crowley's early students, Charles Stansfeld Jones (a.k.a. Frater Achad), the Aeon of Ma'at has already arrived or overlaps the present Aeon of Horus.
The Pandaemonaeon is associated with Chaos magic, Peter J. Carroll, Ray Sherwin, and the Illuminates of Thanateros. It is seen as the Aeon when all past Aeons would exist together, outlined in Carroll's Liber Kaos.
The Aeon of Set[i] (began in 1975) is associated with Michael Aquino's and founding of the Temple of Set. This aeon is associated with the golden mean and golden ratio as symbolized by the pentagram. The magical formula is Xeper. Kenneth Grant's Typhonian Order has discovered a Setian current which implies an Aeon of Set[i]; an esoteric Aeon wherein Death himself dies.
Not all Thelemites believe in a clear succession of Aeons. Sometimes Crowley compared the Word of Horus with other formulas, whose reigns appear to overlap with the Aeon of Osiris and/or Isis. From his The Confessions of Aleister Crowley:
There are many magical teachers but in recorded history we have scarcely had a dozen Magi in the technical sense of the word. They may be recognized by the fact that their message may be formulated as a single word, which word must be such that it overturns all existing beliefs and codes. We may take as instances the Word of Buddha-Anatta (absence of an atman or soul), which laid its axe to the root of Hindu cosmology, theology and psychology, and incidentally knocked away the foundation of the caste system; and indeed of all accepted morality.
- Crowley, Aleister. (1973). The Heart of the Master. Montréal : 93 Publishing.
- ____. (1996). Little Essays Toward Truth. Tempe, AZ : New Falcon Publishing
- ____. (1974). Equinox of the Gods. New York, NY : Gordon Press.
- Thelemapedia. (2004). Aeon. Retrieved April 16, 2006.