Introduction (Isagoge) (1126–1198 AD) and Porphyry (234–). Monfredo de Monte Imperiali
Liber de herbis, 14th century. Porphyry is best known for his contributions to philosophy. Apart from writing the
Aids to the Study of the Intelligibles (Ἀφορμαὶ πρὸς τὰ νοητά;
Sententiae ad Intelligibilia Ducentes), a basic summary of Neoplatonism, he is especially appreciated for his Introduction to Categories—also known in Latin as
Introductio in Praedicamenta or
Isagoge et in Aristotelis Categorias Commentarium—a very short work often considered to be a commentary on
Aristotle's
Categories, hence the title. According to , however, the correct title is simply
Introduction (Εἰσαγωγή
Isagoge), and the book is an introduction not to the
Categories in particular, but to logic in general, as it includes the theories of predication, definition, and proof. The
Introduction describes how qualities attributed to things may be classified, famously breaking down the philosophical
concept of substance into the five components
genus,
species,
difference,
property, and
accident. Porphyry's discussion of
accident sparked a long-running debate on the application of
accident and essence. As Porphyry's most influential contribution to philosophy, the
Introduction to Categories incorporated Aristotle's logic into Neoplatonism, in particular the doctrine of the
categories of being interpreted in terms of entities (in later philosophy, "
universal").
Boethius'
Isagoge, a Latin translation of Porphyry's
Introduction, became a standard medieval textbook in European schools and universities, which set the stage for medieval philosophical-theological developments of logic and the
problem of universals. In medieval textbooks, the all-important
Arbor porphyriana ("Porphyrian Tree") illustrates his logical classification of substance. To this day, taxonomy benefits from concepts in Porphyry's Tree, in classifying living organisms (see
cladistics). Porphyry's invention of the "Porphyrian Tree" is noted as the first proper commentary made on Aristotle's work. '' (Porphyrian tree) used to comment on Aristotle's work by
Purchotius (1730),
Boethius (6th century), and
Ramon Llull (ca. 1305). The
Introduction was translated into Arabic by
Abd-Allāh ibn al-Muqaffaʿ from a Syriac version. With the Arabicized name
Isāghūjī (إيساغوجي) it long remained the standard introductory logic text in the Muslim world and influenced the study of theology, philosophy, grammar, and jurisprudence. Besides the adaptations and epitomes of this work, many independent works on logic by Muslim philosophers have been entitled Isāghūjī.
Philosophy from Oracles (De Philosophia ex Oraculis Haurienda) Porphyry is also known as an opponent of
Christianity and defender of
Paganism; his precise contribution to the philosophical approach to traditional religion may be discovered in the fragments of
Philosophy from Oracles (Περὶ τῆς ἐκ λογίων φιλοσοφίας;
De Philosophia ex Oraculis Haurienda), which was originally three books in length. There is debate as to whether it was written in his youth (as Eunapius reports
Other works Porphyry was opposed to the
theurgy of his disciple
Iamblichus. Much of Iamblichus' mysteries is dedicated to the defense of mystic theurgic divine possession against the critiques of Porphyry. French philosopher
Pierre Hadot maintains that for Porphyry, spiritual exercises are an essential part of spiritual development. Porphyry was, like
Pythagoras, an advocate of
vegetarianism on spiritual and ethical grounds. These two philosophers are perhaps the most famous vegetarians of classical antiquity. He wrote the
On Abstinence from Animal Food (Περὶ ἀποχῆς ἐμψύχων;
De Abstinentia ab Esu Animalium), advocating against the consumption of animals, and he is cited with approval in vegetarian literature up to the present day. He believed that everything was created for mutual advantage, and vegetarianism was a way to preserve universal harmony of nature. Porphyry also wrote widely on
music theory,
astrology, religion, and philosophy. He produced a
History of Philosophy (
Philosophos Historia) with
vitae of philosophers that included a life of his teacher, Plotinus. His life of Plato from book iv exists only in quotes by
Cyril of Alexandria. His book
Vita Pythagorae on the life of
Pythagoras is not to be confused with the book of the same name by
Iamblichus. His commentary on
Ptolemy's Harmonics The
testimonia are published in Andrew Smith (ed.),
Porphyrius, Porphyrii Philosophi fragmenta. Fragmenta Arabica David Wasserstein interpretante, Berlin: Walter de Gruyter, 1993. •
A Treatise Concerning the Secret Doctrines of the Philosophers. Mentioned by Eunapius according to John Toland in "Clidophorus, or of the Exoteric and Esoteric Philosophy." Eunapius says that Porphyry "commended the medicine of perspicuity, and tasting it by experience, wrote "A Treatise Concerning the Secret Doctrines of the Philosophers", which they involv'd in obscurity, as in the Fables of the Poets, but which he brought to light." • There is a fragment attributed to Porphyry in
Shem-Tov ibn Falaquera's ''De'ot ha-Filusufim'', from the 13th century. It is a
Hebrew translation from an unknown
Arabic translation of a lost work. Gad Freudenthal and Aaron Johnson tentatively accept its authenticity.
Uncertain attribution •
Ad Gaurum (of uncertain attribution). Edition: K. Kalbfleisch. Abhandlungen der Preussischen Akadamie der Wissenschaft. phil.-hist. kl. (1895): 33–62. Translation: J. Wilberding,
To Gaurus On How Embryos are Ensouled,
and On What is in our Power.
Ancient Commentators on Aristotle Series, R. Sorabji (ed.), Bristol: Classical Press, 2011. • #6 and #9 in
Corpus dei Papiri Filosofici Greci e Latini III: Commentari – (Florence: Leo S. Olschki, 1995) may or may not be by Porphyry. ==See also==