Chapter 17: On the power of music

1. And without music there can be no perfect knowledge, for there is nothing without it. For even the universe itself is said to have been put together with a certain harmony of sounds, and the very heavens revolve under the guidance of harmony. Music rouses the emotions, it calls the senses to a different quality.

2. In battles, too, the music of the trumpet fires the warriors, and the more impetuous its loud sound the braver is the spirit for the fight. Also, song cheers the rowers. For the enduring of labors, too, music comforts the mind, and singing lightens weariness in solitary tasks.

3. Music calms overwrought minds also, as is read of David, who by his skill in playing rescued Saul from an unclean spirit. Even the very beasts and snakes, birds and dolphins, music calls to hear its notes. Moreover whatever we say or whatever emotions we feel within from the beating of our pulses, it is proven that they are brought into communion with the virtues through the musical rhythms of harmony.

Chapter 18. On the three parts of music.

1. There are three parts of music, namely, _harmonica_, _rhythmica_, _metrica_. _Harmonica_ is that which distinguishes in sounds the high and the low. _Rhythmica_ is that which inquires concerning the succession of words as to whether the sound fits them well or ill.

2. _Metrica_ is that which learns by approved method the measure of the different metres, as for example, the heroic, iambic, elegiac, and so on.

Chapter 19. On the triple division of music.

1. It is agreed that all sound which is the material of music is of three sorts. First is _harmonica_, which consists of vocal music; second is _organica_, which is formed from the breath; third is _rhythmica_, which receives its numbers from the beat of the fingers.

2. For sound is produced either by the voice, coming through the throat; or by the breath, coming through the trumpet or tibia, for example; or by touch, as in the case of the cithara or anything else that gives a tuneful sound on being struck.