Neoplatonism and Gnosticism
Gnosticism refers to a collection of religious groups originating in Jewish religiosity in Alexandria in the first few centuries CE. Neoplatonism is a school of Hellenistic philosophy that took shape in the 3rd century, based on the teachings of Plato and some of his early followers. While Gnosticism was influenced by Middle Platonism, neoplatonists from the third century onward rejected Gnosticism. Nevertheless, Alexander J. Mazur argues that many neoplatonic concepts and ideas are ultimately derived from Sethian Gnosticism during the third century in Lower Egypt, and that Plotinus himself may have been a Gnostic before nominally distancing  himself from the movement. Gnosticism. Gnosticism originated in the late first century CE in nonrabbinical Jewish sects and early Christian sects, and many of the Nag Hammadi texts make reference to Judaism, in some cases with a violent rejection of the Jewish God. Sethianism may have started as a pre-Christian tradition, possibly a syncretic Hebrew Mediterranean baptismal movement from the Jordan Valley, with Babylonian and Egyptian pagan elements, and elements from Hellenic philosophy. Both Sethian Gnostics and the Valentinian Gnostics incorporated elements of Christianity and Hellenic philosophy as it grew, including elements from Plato, middle Platonism and Neo-Pythagoreanism . Earlier Sethian texts such as Apocalypse of Adam show signs of being pre-Christian and focus on the Seth of the Jewish bible. Later Sethian texts are continuing to interact with Platonism, and texts such as Zostrianos and Allogenes draw on the imagery of older Sethian texts, but utilize "a large fund of philosophical conceptuality derived from contemporary Platonism, (that is late middle Platonism) with no traces of Christian content." Scholarship on Gnosticism has been greatly advanced by the discovery and translation of the Nag Hammadi texts, which shed light on some of the more puzzling comments by Plotinus and  Porphyry regarding the Gnostics. It now seems clear that "Sethian" and "Valentinian" gnostics attempted "an effort towards conciliation, even affiliation" with late antique philosophy. Platonism. By the third century, Plotinus had shifted Platonist thought far enough that modern scholars consider the period a new movement called "neoplatonism". Philosophical relations. Gnostics structured their world of transcendent being by ontological distinctions. The plenitude of the divine world emerges from a sole high deity by emanation, radiation, unfolding and mental self-reflection. The technique of self-performable contemplative mystical ascent towards and beyond a realm of pure being, which is rooted in Plato 's "Symposium" and was common in Gnostic thought, was also expressed by Plotinus. Divine triads, tetrads, and ogdoads in Gnostic thought often are closely related to Neopythagorean arithmology. The trinity of the "triple-powered one" (with the powers consisting of the modalities of existence, life and mind) in Allogenes mirrors quite closely the neoplatonic doctrine of the Intellect differentiating itself from the One in three phases, called Existence or reality (hypostasis), Life, and Intellect (nous). Both traditions heavily emphasize the role of negative theology or apophasis, and Gnostic emphasis on the ineffability of God often echoes Platonic (and neoplatonic) formulations  of the ineffability of the One or the Good. There were some important philosophical differences. Gnostics emphasized magic and ritual in a way that would have been disagreeable to the more sober neoplatonists such as Plotinus and Porphyry, though perhaps not to later neoplatonists such as Iamblichus. Gnostics were in conflict with the idea expressed by Plotinus that the approach to the infinite force, which is the One or Monad, cannot be through knowing or not knowing. Although there has been dispute as to which gnostics Plotinus was referring to, it appears they were Sethian. Neoplatonist objections. In the  third century CE, both Christianity and neoplatonism reject and turn against Gnosticism, with neoplatonists as Plotinus, Porphyry and Amelius attacking the Sethians. John D. Turner believes that this double attack led to Sethianism fragmentation into numerous smaller groups (Audians, Borborites, Archontics and perhaps Phibionites, Stratiotici, and Secundians). Plotinus' objections seem applicable to some of the Nag Hammadi texts, although others such as the Valentinians, or the "Tripartite Tractate", appear to insist on the goodness of the world and the Demiurge. In particular, Plotinus seems to direct his attacks at a very specific sect of Gnostics, most notably a sect that  held anti-polytheistic views, anti-daemon views, expressed anti-Greek sentiments, believed magic was a cure for diseases, and preached salvation was possible without struggle. Certainly, the aforementioned points are not part of any scholar definition of Gnosticism, and might have been unique to the sect Plotinus had interacted with. Plotinus raises objections to several core tenets of Gnosticism, although some of them might have come from misunderstandings: Plotinus states that he did not have the opportunity to see the Gnostics explain their teachings in a considerate and philosophical manner. Indeed, it seems most of his conceptions of Gnosticism had  come from foreign preachers that he perceived as harboring resentment against his homeland. Nonetheless, the major differences between Plotinus and Gnostics can be summarized as follows: Plotinus himself attempted to summarize the differences between neoplatonism and certain forms of Gnosticism with an analogy: