Birger A. Pearson (2007) Ancient Gnosticism: Traditions And Literature, Fortress Press.
The word "Gnosticism" is based on the Greek word gnostikos ("gnostic") applied in antiquity to people who claimed a special kind of religious "knowledge" (gnosis), and for whom that knowledge edge served as the basis of their salvation. I try to define what sort of "knowledge" it is that is the key ingredient in "Gnosticism." The approach that I take to the evidence is that of a critical historian of ancient religions.
The earliest evidence we have for ancient Gnosticism comes from the first century of our era. Since no religion or religious movement takes shape in a vacuum, I discuss something of the cultural and religious environment of the first-century Graeco-Roman world. I argue that ancient Platonism, on the one hand, and ancient Judaism, on the other, provided the most ancient Gnostic teachers and prophets with the ingredients they used in creating a religion of salvation based on gnosis. (Kindle Locations 85-90)
The earliest evidence we have for ancient Gnosticism comes from the first century of our era. Since no religion or religious movement takes shape in a vacuum, I discuss something of the cultural and religious environment of the first-century Graeco-Roman world. I argue that ancient Platonism, on the one hand, and ancient Judaism, on the other, provided the most ancient Gnostic teachers and prophets with the ingredients they used in creating a religion of salvation based on gnosis. (Kindle Locations 85-90)
He describes 'Sethian' Gnosticsm as 'Classic' Gnothicism: "one of the two most important manifestations of ancient Gnosticism" (named after the third son of Adam in the Hebrew Bible). The other being Valentinian Gnosticism.
He posits that
"Gnosticism originated in a Jewish environment. The earliest attested mythological logical systems of "Sethian" or "Classic" Gnosticism are made up of innovative reinterpretations of biblical and Jewish traditions, especially Jewish traditions of biblical interpretation." (Kindle Locations 104-105)
He says some sects mentioned in the writings of some church fathers, such as the "Cainites", [probably] never existed.
Valentinus, the greatest ancient [Christian] Gnostic teacher of all, taught first Alexandria and then in Rome. Pearson describes seven Valentinian tracates in the Nag Hammadi collection.
The Nag Hammadi codices include a large number of Gnostic writings preserved in Coptic, many whose sectarian affiliations are unclear.
Basilides, who taught in Alexandria in the early second century, utilized Gnostic traditions in devising his own version of Christianity. He was the very first early Christian teacher to write commentaries on texts that would eventually become part of the New Testament canon. (Kindle Locations 106-108)
Pearson also discusses Basilides' son and pupil Isidore.
Hermetism is another religious current that emphasized self-knowledge knowledge as the basis for salvation. This religion arose in Alexandria, Egypt, probably in the first century CE. It features the Egyptian god Thoth in Greek guise as "Thrice-Greatest Hermes," who gives revelatory instruction to his "son" and other pupils. (Kindle Locations 117-120).
Pearson introduces two of the Greek Hermetic texts, and three Hermetic texts in the Nag Hammadi collection.
He discusses the Gospel of Thomas, which he does not consider to be a "Gnostic" writing, but included it along with related texts that represent what he calls "Thomas Christianity", a variety of Christianity which emphasized self-knowledge which ''was at home in Syria from the second century on.'' He also introduces another Nag Hammadi tractate representing Thomas Christianity.