(Σιβύντιος), a reader and a slave of the orator Theodectes of Phaselis, who died before B. C. 333, was the first slave who professed the art of oratory. He wrote some works on rhetoric, which are mentioned by Suidas (s.v.) (Comp. Westermann, Geschichte der Griech. Beredtsamkeit, § 50, n. 6.)
A Dictionary of Greek and Roman biography and mythology
Smith, William
A Dictionary of Greek and Roman biography and mythology. William Smith, LLD, ed. 1890