In gnostic belief systems, an “aeon” is characterized as the transition from immaterial to material, from nominal to sensible, and is created by a flaw, passion, or sin.
While, in the religion of Thelema, aeons are a system of dividing the history of humanity, in which each aeon is accompanied by its own forms of “magical and religious expression”.
For example, the Aeon of Isis was believed by Thelemites to have occurred during prehistory, when mankind worshipped the goddess (characterized as Isis) and was more maternal in nature. This was followed by the Aeon of Osiris, a period taking place in classical and mediaeval centuries, when humanity worshipped the singular male god (symbolized by Osiris), thus resulting in a patriarchal society. The third aeon is considered the Aeon of Horus, which many believe we are perhaps entering into now, and is controlled by the child-god. This new aeon is believed to be the time of self-realization and self-actualization…the balance of the two sides (male and female) which results in a dawn of new creativity and consciousness.