SETHIAN GNOSTIC COSMOLOGY
Aeons of aeons
One of the most common features of Sethian Gnostic texts was their cosmological explorations and speculations. On this, the texts themselves can sometimes be difficult to penetrate and easy to misenterpret, while many of the expositions of said cosmologies tend to either be long and (sometimes) equally dense academic publications, or simple diagrams that offer little by way of explanation or clarification.
As such, what we attempt to present below should serve as an easy reference guide to both the aeons and the ontological layers of the Pleroma as seen through Sethian eyes. What follows is a harmonisation of current scholarly opinions, taking into account the differing descriptions offered by the surviving texts themselves. Concise, but hopefully comprehensive.*
Principle elements, in descending order
The Father, the Monad, the 'Great Invisible Spirit' (also known as the Virginal Spirit and the 'Triple Powered' One for its Platonic attributes of Life, Mind, and Existence). The supreme transcendent deity, or godhead. Traditionally described largely using negative theology rather than in definitive terms, it is unknowable, beyond being and beyond comprehension. Despite the remote serenity ascribed to it the Invisible Spirit is essentially an intellect and its thinking results in its evolution into an'entirety' (the Pleroma) with a complex structure of aeons. These aeons are simultaneously places and actors in the Gnostic myth. They mostly represent ideal intellectual qualities, virtues, or abstractions. The aeons that make up the Pleroma result from the Invisible Spirit's knowledge of itself, They are its intellect in all its complexity. Every subsequent aeon both ultimately comes from, and is a part of the Monad, whose only direct creative act was the emanation by self reflection of Barbelo, the Mother and the 'First Thought'. Though all ultimately derives from the Monad, it had no direct role in the creation of the world or material cosmos.
The Mother. Barbelo, Pronnoia, Protennoia (also known as Incorruptibility, and the 'Mother-Father'). The second principle of Sethian Gnosticism, Barbelo is the First Thought of the Invisible Spirit - the universal intellect containing all potential archetypes and forms (and thus also described as androgynous), the highest level of pure determinate being. Like the Father above her, Pronnoia is both one-in-many, yet singular and unified. The sub-aeons of Barbelo are sometimes presented by the Sethians as distinct aeons and sometimes as functional attributes or ontological levels of being within the greater Barbelo aeon. The ancient Sethians speculated at great length on the contents and mysteries of Barbelo, and explored them in visionary ascents. The earlier texts (such as the Apocryphon of John) name the subaeons of Barbelo as Foreknowledge, Incorruptibility, Life Eternal, and Truth, or Voice , Speech, and Word, while the later texts (such as Zostrianos) name them as Kalyptos, Protophanes, and Autogenes (the Son, who is both a part of Barbelo and at once her first distinct emanation), symbolising potential existence, manifestation, and actualisation. The subaeon of Protophanes is also described as the highest achievable plane of existence for enlightened souls, 'all-perfect ones' that remain distinct intelligences yet unified with the objects of their contemplation - the ideal forms of the Barbelo aeon.
The Son, Autogenes, Christos (Christ, 'the anointed'), the Logos. The direct emanation and 'only child' of both the Invisible Spirit and Barbelo, a Platonic demiurgic figure in the purely spiritual, Pleromatic, sense, shaping the divine energy from above into the ideal Forms and divine archetypes of the Pleroma. Autogenes is also a mediator between the upper aeons and Self Generated aeons below him for which he is responsible, thus he is oriented toward both above anod below. With him dwell the 'perfect individuals' that are no longer subject to reincarnation. It is also this aeon that descended into the world (in some tellings through the heavenly Seth) and into the body of Jesus of Nazareth as the Saviour for the purpose of rectifying Sophia's mistake and revealing a message of spiritual liberation (gnosis) to mankind.
The Four Luminaries, 'standing before the divine Autogenes' Harmozel, Oraiel, Davithe, and most prominently Eleleth are emanated by Autogenes as celestial places, Harmozel for Adamas (Geradamas), Seth (the Great Seth, Emmacha Seth) in Oraiel, and his progeny in Davithe, while repentant or previously ignorant souls dwell with Eleleth. As personifications, the Four Luminaries also sometimes enter the Gnostic mythological narrative directly, such as the dramatic appearance of Eleleth in the Hypostasis of the Archons. It is also from the Four Luminaries directly that the subsequent twelve aeons are emanated.
The Self-Generated Aeons, everything that is contained within or has been emanated from the Four Luminaries can be found in this somewhat populous ontological layer of the Pleroma. The twelve aeons representing fundamental elements of the Pleroma: Grace, Truth, and Form that come from Harmozel; Insight, Perception, and Memory from Oroiael; Understanding, Love, and Idea from Daveithai; Perfection, Peace and of course Sophia (Wisdom) come from Eleleth.
Sophia (Wisdom), Metanoia (Repentance) the last of the classical Gnostic aeons to be emanated, it is through an error or misguided act of creation on her part that the material universe and its demiurge came into being. The plight of Sophia is seen as analogous of human experience, having fallen into disorder and error she then repents and receives both forgiveness and restoration. Told either in terms of her acting alone in imitation, of the Invisible Spirit and without her male half (partner), or acting at the command of Eleleth yet committing some error that results in a portion of her 'light' being stolen by the Archon of Creation (fragments of which would go on to become the souls of humanity).
Repentance, a lower aeonic realm and ontological plane of being associated with the repentance of Sophia and perhaps created by her passion. It is said to contain immortal souls that have renounced the material world and are capable of ascent into the Pleroma proper, yet are in need of 'repentance' - perhaps intended here to mean a process of learning and detachment from the material world.
Sojourn, another realm, like Repentance, located between the Pleroma and the universe of material creation below, and perhaps associated with the lowest descent of the aeon Sophia. A place of human souls between incarnations - some may progress upward toward the Pleroma, while the rest will be subject to reincarnation back into the world.
Saklas, Yaldabaoth, Samael (also known as 'the Archon of Creation', the 'Counterfeit Spirit' and 'the Demiurge') - the shaper of the material cosmos and the one that set its rules in place. In the classic Gnostic myth he is the result of Sophia's misguided act of creation and remains largely ignorant of the Pleroma. Capable of creating beauty, he shaped the material world in imperfect imitation of what he had seen of the Pleroma, yet also of cruelty and arrogance - and so when appearing as a personified figure in the mythological narrative, he tends to exemplify tyrannical and narcissistic personality traits, unable to acknowledge or truly understand what is above and beyond him. Occasionally described as having a female counterpart named Nebruel, or simply being partnered with 'Matter'.
The Archons, the Rulers, the Powers, the 'Thirteen Aeons' (composed of the 12 Archons plus the demiurge). Created by the demiurge these powers serve as spiritual embodiments of the elements that separate the material world from the Pleroma, as well as the result of the demiurge's attempt to copy the true aeonic emanations. It is these powers that the human soul must overcome and trascend in order to ascend to the Pleroma above.
The Material Cosmos (Kenoma), 'Nature', the observable universe and the realm of impermanent matter in which we presently find ourselves. A place of 'passion and division', in some ways a reflection of the beauty in the Pleroma, yet imperfect due to its unstable, impermanent nature (in comparison to the ideal forms of the Pleroma), and the presence of suffering and death within it. Human souls are compelled to continually reincarnate into this realm by the archonic powers until such a time as they are able to transcend it and 'return' to the Pleroma above.
Other elements of Note:
Epinnoia (Insight, divine afterthought), a lower salvific double or emanation of Barbelo, closely related to Sophia. The Epinnoia, as the spiritual Eve, descends into the body of the earthly Eve in much the same way that Christ descended into the body of the earthly Jesus. The term is also used in some texts as an alternate title for Sophia herself.
The Logos (the Word), more of a function than a distinct aeon, 'the Logos' is any aeon that descends into or is active in the world; thus Pronoia, Autogenes, or Seth can all variously be described as such.
Yoel, or Youel, a lower double of Barbelo/Pronoia who functions as a revealer and guide to the Pleroma in later Sethian texts, where she appears as a narrative character. An example of the 'Mother' archetype despite also being described as the 'Male Virgin'.
The Doxomedon, or Domedon Doxomedon, a term used in some Sethian texts to descibe the highest aeonic pentad found in the more elaborate cosmological accounts; the Invisible Spirit, Barbelo, the Tripple Male Child, Youel, and Esephech.
The Great Christ (the 'Triple Male Child'), an upper reflection of Autogenes, the Son. Present in some texts as the aeonic partner of Yoel.
Yesseus Mazaraeus Yessedekeus, (Jesus of Nazareth, the Righteous) a Sethian alteration for the name of the earthly 'Jesus of Nazareth', the mortal sage who bore the spirit of the Christ and in who's name one is baptised in the 'living water' (the essence of the Pleroma). After his sacrifice his spirit was said to have been lifted to be among the self-generted aeons of Autogenes,
Ephesech ('the Child of the Child'), or Esephech, an emenation of Yoel and the Triple Male Child. An example of the 'Son' archetype and thus likely related to the Autogenes aeon. Like Yoel he also serves as a guide and revealer for those that ascend into the Pleroma.
The Ministers of the Luminaries, Gamaliel (the most prominent of the four), Gabriel, Samblo, and Abrasax. Aeonic assistants that act on behalf of the Four Luminaries.
Zoe, described as the daughter of Sophia in some texts, in which she also becomes a partner to the redeemed archon Sabbaoth. She is also associated with Epinnoia and thus the spiritual Eve.
Sabbaoth, originally an archon in service to Saklas, he repents upon seeing the light of the Pleroma and as such is elevated above his father to the Eighth Heaven (perhaps analogous to the 'Repentance and 'Sojourn' of later Sethian texts - a plane of existence above the demiurgic realms, yet outside the Pleroma proper) where he sits alongside Zoe. Sometimes read as an example of the universal salvation possible from the Sethian point of view.
Michaeus, Michar & Mnesinous, minor aeonic helpers that act as baptismal assistants during spiritual ascents to the Pleroma. Generally considered to be among the 'Self-Generated Aeons'.
The Luminaries of The Barbelo Aeon, Salamex, Semen, and Arme. A trio of aeonic assistants mentioned in some later Sethian texts, who act as helpers and revealers within the aeon of Babelo.
The 'Aeonic Copies', a somewhat mysterious concept mentioned in some texts dealing with ascent to the Pleroma. They seem to constitute 'copies' or a lower reflection of the the three ontological layers above them - Sojourn, Repentance and the Self-Generated Aeons, functioning as a kind of holding area for a part of the human spirit not incarnated into the world, and as a place of training and preparation for the complete soul's eventual ascent to the 'truly existent' aeons. There also seems to be an archonic association with this layer of reality, though despite this it is not described in entirely negative terms within the texts themselves.
The Unknown Silent One, a divine power that transcends even the conventional Sethian Monad or 'Invisible Spirit'. The upper reaches of the Monad are sometimes described separately in some texts, but it is only in Marsenes that the concept of the 'Unknown Silent One' is described in entirely distinct terms - a kind of Monad above the Monad, about which nothing can be known.
* With thanks to professors John Turner and Dylan Burns, whose comprehensive work in the field has informed the above.
It should also be noted that though the above is comprehensive it is by no means exhaustive and does include names that only occur only once and are of lesser importance, or whose meaning/nature is unknown to scholarship.