Music has two modes of expression in the voice and in the body;1 for both voice and body require to be controlled by appropriate rules. Aristoxenus divides music, in so far as it concerns the voice, into rhythm and melody, the one consisting in measure, the latter in sound and song. Now I ask you whether it is not absolutely necessary for the orator to be acquainted with all these methods of expression which are concerned firstly with gesture, secondly with the arrangement of words and thirdly with the inflexions of the voice, of which a great variety are required in pleading.