Isagoge

Traditions

Neoplatonism

Role in the tradition

Primary source Written from inside the tradition: scripture, revelation, a grimoire, a manifesto or a practical treatise.

Public attention

Major Wikipedia has an article about it in 20 languages.

No free edition was found at sacred-texts.com, Project Gutenberg, esotericarchives.com, archive.org or Wikisource.

The Isagoge or "Introduction to Aristotle's Categories", written by Porphyry in Greek and translated into Latin by Boethius, was the standard textbook on logic for at least a millennium after his death. It was composed by Porphyry in Sicily during the years 268–270, and sent to Chrysaorium, according to all the ancient commentators Ammonius, Elias, and David. The work includes the highly influential hierarchical classification of genera and species from substance in general down to individuals, known as the Tree of Porphyry, and an introduction which mentions the problem of universals.

From the Wikipedia article Isagoge, revision 1359536617, under CC BY-SA 4.0. Wikidata Q642697: “book by Porphyrius”.