Porphyrian tree

In philosophy (particularly the theory of categories), the Porphyrian tree or Tree of Porphyry is a classic device for illustrating a "scale of being" (Latin: 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.

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.

The extremes (the terms that jut out to the left and right), containing the differentiae, we can take as analogous to the branches of a tree: The diagram shows the highest genus to be substance.

The diagram shows that the genus substance has two differentia, namely, "thinking" and "extended."