(Bacchus), surnamed the Old; a Greek author whose place and time of birth are unknown. He wrote an Introduction to the Art of Music, in the form of questions and answers, apparently intended for the use of schools. Its title, Εἰσαγωγὴ τῶν ἀρχῶν μουσικῆς, might lead one to suppose that it contains some explanations of the art of composing or performing music; but it treats merely of sounds, intervals, systems, &c. Meibomius published the first part of Bacchius' work, with a Latin translation and notes, in his Antiquae Musicae Auctores, Amstel. 1652; but unaccountably omitted the second part, although he had a copy of it. In the royal library of Paris there exists a MS. copy of that second part, but it has not yet been published, except through a bad French translation of the whole work, given by Mersenne in his Harmonie Universelle, 1627.