  Discussion of the commentary on Aristotle’s Meteorology (with the co-called “chemical treatise” as its fourth book) prompts the question of the identity of the Neoplatonist Olympiodorus with another figure carrying precisely the same name who appears in the alchemist tradition. Four extant manuscripts of an alchemical work that purports to be a commentary on Zosimus’ Kat’ energeian (On Activity) state that the piece was written by “Olympiodorus, the Alexandrian philosopher” (see §6 below). The alchemical treatise starts out as a commentary on Zosimus (of Panopolis, not the 5th c. C.E. historian), explaining a small passage in some detail, but then continues in the vein of a didactic letter written to an unnamed fellow alchemist (called ‘friend of the Muses’ at one point); it ‘explains’ how to join scattered parts of gold and purify metals, emphasizes the significance of ‘divine water’ (whatever that is) and so on and so forth. The author knows a smidgen about the Presocratics (whom he regards as alchemists), but next to nothing about Plato and Aristotle; instead, he can quote at length from Zosimus, Hermes, Petasius, Pelagius, and a “divine Mary” — not the mother of Jesus but a Jewish sage elsewhere attested in the alchemist tradition.