Porphyrian tree

The Porphyrian tree or Tree of Porphyry is a classic device for illustrating a "scale of being" (scala praedicamentalis), attributed to the 3rd century CE Greek neoplatonist philosopher and logician Porphyry, and revived through the translations of Boethius.^[1]

Porphyry suggests the tree in his introduction ("Isagoge") to Aristotle's Categories. Porphyry presented Aristotle's classification of categories in a way that was later adopted into tree-like diagrams of two-way divisions, which indicate that a species is defined by a genus and a differentia and that this logical process continues until the lowest species is reached, which can no longer be so defined. No illustrations or diagrams occur in editions of Porphyry's original work; diagrams were eventually made, and became associated with the scheme that Porphyry describes, following Aristotle.

Porphyry's Isagoge was originally written in Greek, but was translated into Latin in the early 6th century CE by Boethius. Translations by Boethius became the standard philosophical logic textbook in the Middle Ages,^[2] and theories of categories based on Porphyry's work were still being taught to students of logic until the late 19th century.