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. Chapter 20. On the first division of music which is called _harmonica_. 1. The first division of music, which is called _harmonica_, that is, modulation of the voice, has to do with comedians, tragedians, and choruses, and all who sing with the proper voice.[260] This [coming] from the spirit and the body makes motion, and out of motion, sound, out of which music is formed, which is called in man the voice. [260] _Qui voce propria canunt._ 2. _Harmonica_ is the modulation of the voice and the concord or fitting together of very many sounds. 3. _Symphonia_ is the managing of modulation so that high and low tones accord, whether in the voice or in wind or stringed instruments. Through this, higher and lower voices harmonize, so that whoever makes a dissonance from it offends the sense of hearing. The opposite of this is _diaphonia_, that is, voices grating on one another or in dissonance. 7. _Tonus_ is a high utterance of voice. For it is a difference and measure of harmony which depends on the stress and pitch of the voice. Musicians have divided its kinds into fifteen parts, of which the hyperlydian is the last and highest, the hypodorian the lowest of all. 8. Song is the modulation of the voice, for sound is unmodulated, and sound precedes song. Chapter 21. On the second division, which is called _organica_. 1. The second division, organica, has to do with those [instruments] that, filled with currents of breath, are animated so as to sound like the voice, as for example, trumpets, reeds, Pan’s pipes, organs, the pandura, and instruments like these.[261] [261] The pandura was a stringed instrument! In the succeeding sections these instruments are briefly described, and the sambuca, another stringed instrument, is also included. Chapter 22. On the third division, which is called _rhythmica_.