Until the third century A. D. the kitharœdic chant was purely Hellenic, as we might surmise from the names of its most famous exponents, such as Terpnos, Menecrates, Diodorus, Chrysogones, Pollion, Echion, and Glaphyros. In the second century Ptolemy, writing his 'Harmonics,’ founded his system of tones and modes on the practice of the kithara and lyre players.[46] Practically all of the pieces which have come down to us from the Græco-Roman period, and which we have noted in the last chapter, belong to the literature of the kithara. The kitharœdic chants were narratives in the style of Timotheus, or lyrics, chiefly hymns to some divinity. These compositions were not in strophic form. The melody was divided into sections of unequal length (_commata_) and varied more or less from one end of the poem to the other. Until the beginning of the fourth century the texts were usually in Greek. The Latin kitharœdic songs, such as those of Horace and Catullus, were scarcely heard except at banquets and private reunions. Greek was, indeed, the prevailing musical language, as we may learn from Vitruvius, who prefaces to the chapter on music in his work on Architecture a warning that musical theory is practically a sealed book to those who do not know Greek.[47] After the removal of the seat of empire to Byzantium in 330 A. D., the use of Greek disappeared, and with it the use of musical notation by means of Greek letters. The transmission of music then became oral and the art of the kithara song and its accompaniments gradually vanished.[48] II