SOURCE: Barnes, Jonathan. Introduction to Porphyry: Introduction, translated by Jonathan Barnes, pp. ix-xxiv. Oxford, Eng.: Clarendon Press, 2003.

In the following essay, Barnes discusses the nature and purpose of Isagoge, which he maintains is not so much an introduction to Aristotle's Categories as it is a primary text and a handbook to philosophy and logic.

For a thousand years and more, Porphyry's Introduction was every student's first text in philosophy. St Jerome learned his logic from it (ep 50 1). Boethius observed that ‘everyone after Porphyry's time who has tackled logic has started with this book’ (in Isag¹ 12.20-21). The Introduction was translated into Syriac, Latin, Armenian, Arabic. It maintained its standing throughout the middle ages, both in the Greek East (where it was also known by way of epitomes and paraphrases) and in the Latin West (where Boethius' translation was vastly influential); it informed the development of Arabic logic and...