Thrasyllus (fl. 1st century BC) was an astrologer and mathematician from the ancient Greek city of Tarentum. He was a contemporary of Augustus, the first Roman Emperor. He is known for having correctly predicted Augustus’ ascension to power, and for having given him advice on various matters. His works are no longer extant, but references to him can be found in various ancient authors. He was also an accomplished mathematician and is credited with having developed a method for solving the Delian Problem, a mathematical puzzle that had been posed by the ancient Greeks.
He is most famous for his work on astrology, which was based on the teachings of the philosopher Plato. He believed that the movements of the planets and stars could be used to predict events and guide people’s lives. He wrote several books on astrology, including On the Fixed Stars, On the Planets, and On the Constellations. He was also the author of the Tetrabiblos, a four-volume work on astrology that was widely read and used during the Middle Ages.
Iulii Firmici Materni Mathesos libri VIII, 2 vols., ed. W. Kroll, F. Skutsch, K. Ziegler, Teubner, Leipzig, 1897-1913 (reprinted 1968). ➤
Harold Tarrant, Thrasyllan Platonism, Cornell University Press, Ithaca, NY, 1993, pp. 215-249. ➤
The Astrological Record of the Early Sages in Greek, trans. Robert Schmidt, ed. Robert Hand, The Golden Hind Press, Berkeley Springs, WV, 1995, pp. 57-60. ➤
Beck, Roger. “The Mysteries of Mithras: A New Account of Their Genesis,” The Journal of Roman Studies, Vol. 88, 1998, pp. 115-128. ➤
Cichorius, Conrad. “Der Astrologe Ti. Claudius Balbillus, Sohn des Thrasyllus.” Rheinisches Museum für Philologie, 76, 1927, pp. 102–105. ➤
Cramer, Frederick H. Astrology in Roman Law and Politics. American Philosophical Society, Philadelphia, PA, 1954. ➤
Dio, Cassius. Roman History. Translated by Earnest Cary, 9 vols., Loeb Classical Library, Harvard University Press, Cambridge, MA, 1914-1927. ➤
Gansten, Martin. “Balbillus and the Method of aphesis,” Greek, Roman, and Byzantine Studies 52, 2012, pp. 587–602. ➤
Krappe, Alexander Haggerty. “Tiberius and Thrasyllus.” The American Journal of Philology, Vol. 48, No. 4 (1927), pp. 359-366. ➤
Laertius, Diogenes. Lives of Eminent Philosophers. 2 vols., trans. R. D. Hicks, Loeb Classical Library, Harvard University Press, Cambridge, MA, 1925. ➤
Oliver, Revilo P. “Thrasyllus in Tacitus (Ann. 6.21).” Illinois Classical Studies 5, 1980, pp. 130-148. ➤
Tacitus. The Annals of Imperial Rome. Translated by Michael Grant, Penguin Books, London, 1956 (rev. ed. 1989). ➤