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.
§ 126. The School of Valentinus. Heracleon, Ptolemy, Marcos, Bardesanes, Harmonius.
Schaff traces the development of Valentinian Gnosticism, though with some difficulty because of the ever-changing ideas of the Gnostics (Schaff 2014, Loc. 18368). In the East, the followers of Valentinus saw Jesus’ body as a pneumatic and heavenly substance, while in Italy they saw it as a psychial thing, which required the coming of the Holy Spirit. Heracleon, flourishing between 170 and 180, wrote a commentary on John, which is known to us through fragments upon which Origen commented, normally by contradicting Heracleon. Both Heracleon and Origen were highly allegorical in their interpretations (Schaff 2014, Loc. 18376). Schaff further mentions Ptolemy, who wrote the Epistle to Flora, attempting to make a convert to Valentinianism (Schaff 2014, Loc. 18383). His root argument is that because God is good He could not make a world that is so evil. Marcos, another follower of Valentinus, focused on numerology and elaborate rituals. Bardesanes, a Syrian, was prominent in the late second and early third centuries. Schaff considers him only marginally a Gnostic but certainly a heretic (Schaff 2014, Loc. 18391). Bardesanes’ son, Harmonius, was largely known for establishing Syrian hymnology, even writing a collection of 150 hymns (Schaff 2014, Loc. 18399). Schaff gives little information about what identifies these figures as Gnostic or not.