October 15, 2021:
I've misunderstood the relationship between Gnosticism and Neoplatonism. I've previously thought of Gnosticism as a variant of Neoplatonism, but Gnosticism is historically prior. Plotinus had Gnostics in his seminar and argued against them, particularly on the cosmological origin of evil, which for Plotinus is more or less simply an automatic artifact or affect of matter rather than a self-conscious if mistaken creator of things.