(Porphyrios). Born circa 233, in Tyre; died 304, in Rome. Ancient Greek philosopher. Representative of Neo-platonism.
A disciple of Plotinus, Porphyry published his master’s works and wrote a description of his life. Porphyry won fame chiefly as a commentator on the works of Plato and Aristotle. His treatise, an Introduction to the Categories of Aristotle, was the principal source through which Aristotelian logic was studied during the Middle Ages. The treatise was also known as the Isagoge [Quinque voces, or On the Five Voices], a reference to the five criteria of a concept: genus, species, differentia, essential attributes, and nonessential or separable accidents. Porphyry’s Categories was supplemented with commentaries and translated many times. (Boethius translated it into Latin.)
In logic the tree of Porphyry illustrates the multilevel subordination of the concepts of genus and species in dichotomous division. Porphyry also wrote many works on mathematics, astronomy, history, and grammar. The lengthy treatise Against the Christians, which contains early examples of biblical criticism, was burned in 448. Only fragments of the work were preserved (see A. B. Ranovich, Classical Critics of Christianity, Moscow, 1935).
A. F. LOSEV
the general term for effusive and paleotypal acidic rocks that have porphyritic textures. Porphyry was originally the name of a unique red rock with large white orthoclase phenocrysts that was widely used for decoration and sculpture in ancient Rome. Orthoclase porphyry, or orthopyre, which closely resembles trachyte, is distinguished from quartz porphyry, which closely resembles liparite (rhyolite). Typically, porphyry has a glassy groundmass replaced by felsite (a submicroscopic graphic granite aggregate) and microlites of albite or orthoclase, as well as by phenocrysts of orthoclase or orthoclase and quartz. The groundmass also often contains biotite and hornblende. Porphyry is commonly found in ancient volcanic strata.