Simeon Seth(i) or Symeon Seth(i) (Greek: Συμεὼν Μάγιστρος Ἀντιοχείας τοῦ Σήθι, "Symeōn Magister of Antioch, son of Sēth", sometimes also "Simeo" and "Sethus") was an 11th-century Byzantine doctor, scholar, and grand Chamberlain (protovestiarius) under Emperor Michael VII Doukas, originally from Antioch. He was a contemporary of Michael Psellos.
He revised Psellos's Σύνταγμα κατὰ στοιχείων περὶ τροφῶν δυνάμεων (TLG no. 3113.002; in Latin the Syntagma de alimentorum facultatibus or De cibarium facultate, "On the Properties of Foods"), which criticizes Galen and emphasizes eastern medical traditions. Paul Moore says "the text is really an explanation of Aetius Amidenus Iatricorum libri xvi, with material drawn from Dioscorides Liber de alimentis. Apparently, Psellos wrote the work for the emperor Constantine IX Monomachos. It was then revised for Michael VII Doukas by Symeon Seth, who wrote a brief introduction (the proem.), made some corrections in the text, omitting some chapters. The work deals with some two hundred and twenty-eight plants and animals." The Syntagma is an important source for Byzantine cuisine and dietetics.
Simeon's work Σύνοψις τῶν φυσικῶν (Conspectus rerum naturalium, "On the things of nature": TLG 3113.003) is a treatise on the natural sciences divided into five books. The first concerns the earth; the second, the elements; the third, the sky and the stars; the fourth, matter, form, nature and the soul (sense perception); the fifth, the final cause and divine providence. The work is heavily influenced by the philosophy of Aristotle.
He learned astronomy from Arabic sources and translated the book of fables Kalilag and Damnag from Arabic to Greek in about 1080. The protagonists in the Greek version are named "Stephanites" and "Ichnelates" (TLG 3113.001).
Seth advanced several proofs that the earth was spherical. He noted that since the sun rises in the east before it sets in the west, it can be afternoon in Persia when it is still morning in Byzantine lands. How do we know this? The same eclipse that was recorded as having taken place in the afternoon by the Persians was recorded in the morning by the Greeks (eastern Romans). Nautical and astronomical proofs are also given. (Physics, 15) 
- Marc Émile Prosper Louis Brunet, Siméon Seth, médecin de l’empereur Michel Doucas; sa vie, son oeuvre. Première traduction en français du traité "Recueil des propriétés des aliments par ordre alphabétique", Delmas, Bordeaux, 1939. (not seen)
- David Deakle, "Simeon Seth on Cannabis (Cognoscenti of Cannabis II)", 2001 doi:10.1300/J175v01n02_03
- The full texts of the 1658 Paris edition and of Langkavel's 1893 Teubner edition are available online. The work is found in Paris manuscripts Codd. parisini græci 36, 1603, 1251, 2154, 2181, 2224, 2228, 2229, 2230, 2231, 2235, 2260, 2301, 2302, 2303, 2308, 2316, 2324, 2510, 2650; Supplément grec nos. 64, 634, 637, 1327; Paris. Coislin 335; and Parisinus latinus 7049, as well as many non-Paris mss. (see Moore, pp. 438-444).
- Howells, John G.; Osborn, M. Livia (1984). A reference companion to the history of abnormal psychology. Greenwood Press. ISBN 9780313242618. Retrieved 3 April 2013.
- "Simeon Seth was the great Orientalist of Byzantine medicine... [he] selected the best, not only from the Greek materia medica but also from Persian, Arabic, and Indian sources". Owsei Temkin, "Byzantine Medicine: Tradition and Empiricism", Dumbarton Oaks Papers 16:95-115 (1962) at JSTOR
- Paul Moore. Iter Psellianum: a Detailed Listing of Manuscript Sources for All Works Attributed to Michael Psellos, Including a Comprehensive Bibliography (Subsidia Mediaevalia 26). Toronto: Pontifical Institute of Mediaeval Studies, 2005 (ISBN 0888443757), p. 437 (entry no. 1045 (CET.DISC.26)).
- A. Delatte, Anecdota Atheniensia et alia, Volume 2 (Paris, 1939), 1-89 (edition of text with historical introduction).
- David Pingree, "Gregory Chioniades and Palaeologan Astronomy", Dumbarton Oaks Papers 18:133-160 (1964)
- Jewish Encyclopedia, 1906 s.v. Kalilah wa-Dimnah; date from G.H. Gérould, "The Ballad of the Bitter Withy" (not seen), cited by Phillips Barry, "The Bridge of Sunbeams", The Journal of American Folklore 27:103. (January–March 1914), pp. 79-89 at JSTOR
- L.-O. Sjöberg, Stephanites und Ichnelates: Überlieferungsgeschichte und Text (Uppsala, 1962).
- Kadellis, Anthony (November 16, 2017). "The Hidden Science and Tech of the Byzantine Empire". Nautilus.