Nechepso and Petosiris

Definition

Nechepso and Petosiris are a pair of names under which a foundational Hellenistic astrological treatise was issued — the writing was credited to them rather than written by them. Nechepso is presented as an Egyptian king, identified by ancient sources with the Saite ruler Necho II of the 26th Dynasty (about 600 BCE), or with a 7th-century king; Petosiris is presented as an Egyptian priest. The treatise came out of Ptolemaic Alexandria around 150 BCE. It is lost, but survives in long quotations by later Hellenistic writers, above all Vettius Valens and Firmicus Maternus.

In Tradition

Hellenistic astrologers, and modern scholars of the Hermetic-Egyptian tradition, treat Nechepso and Petosiris as the names that gave the technical astrology built in Greco-Roman Alexandria an authoritative "Egyptian" pedigree. They sit in a lineage — Hermes Trismegistus, then Asclepius/Imhotep, then Petosiris and Nechepso — with the doctrine said to have come down from the divine Mercury through Asclepius and Hanubius before being entrusted to the human pair.

In Practice

Hellenistic astrologers cite Nechepso and Petosiris for particular techniques. Vettius Valens (Anthologies III, 11) credits Nechepso with a way of judging length of life from the Lot of Fortune — a calculated point in the chart — using it to find the aphetēs and the giver-of-years. Firmicus Maternus credits the pair with the Thema mundi, the chart of the birth of the world, anchored to a 15-degree configuration with Sirius rising. The Suda mentions a treatise Astrologumena under Petosiris, and Riess (1891) catalogued at least fifteen books ascribed to Nechepso, covering the Lot of Fortune, astrological medicine, and astral magic. Modern historians use these citations as the main evidence for the Egyptian-Hermetic groundwork of Hellenistic technique, while noting — with Greenbaum, Heilen, and Quack — that the actual writing dates to mid-2nd-century-BCE Alexandria, not pharaonic Egypt.

Historical Origin

The earliest datable citations are in Vettius Valens, Anthologies (2nd century CE), and Firmicus Maternus, Mathesis (4th century CE); the pair is also cited by Hephaestio of Thebes, Rhetorius, and the Anonymous of 379, which lists Hermes, then Nechao, Cerasphorus, Petosiris, and Nechepso. The fragments are edited in Riess, Nechepsonis et Petosiridis fragmenta magica (1891-1892). Modern study: Holden, A History of Horoscopic Astrology (2006); Greenbaum, The Daimon in Hellenistic Astrology (2016); Belmonte and Lull, In Search of Cosmic Order (2009).

Definition

In Tradition

In Practice

Historical Origin

Further Reading