Schaff, Philip. History of the Christian Church (The Complete Eight Volumes in One). Amazon Kindle Edition, 2014.
Volume 2, Ante-Nicene Christianity A.D. 100-325, “Chapter 11. The Heresies of the Ante-Nicene Age” Sections 112-136, Loc. 17655-18757.
§ 120. Schools of Gnosticism.
Because Gnosticism was very speculative, Schaff notes that there were multiple schools of thought within it. In general, he divides Gnosticism into two groups: Egyptian and Syrian (Schaff 2014, Loc. 18117).The Egyptian school showed a great influence of Platonism and the idea of emanations, while the Syrians were characterized by Parsism and dualism. Schaff also finds in Asia Minor a group following Marcion.
From a doctrinal point of view, “Gnosticism appears in three forms, distinguished by the preponderance of the heathen, the Jewish, and the Christian elements respectively in its syncretism” (Schaff 2014, Loc. 18125). Schaff continues by listing no less than sixteen streams of Gnostic thought, dividing them doctrinally, before reminding the reader that all forms of Gnosticism are, in essence, non-Christian.
Schaff further finds three branches of ethics in Gnosticism. There is a theosophic version, a more ascetic version, and an antinomian version (Schaff 2014, Loc. 18132). In future sections, Schaff will begin tracing Gnostic developments chronologically.