Hoc in volumine haec opera continentur

... say in four. The whole diatessaron is in thirty. Therefore, harmony is modulated by three twelve-parts, magnitude 43 and 24. Soft chroma is by 4 and 14 and 22. Sesquialter chroma is by four and a half, four and a half, and 21. Tonizum chroma is by 6 and 6 and 18. Soft diatonum is by 6 and 9 and 15. And syntonum intense/tuned is by 6 and 12 and 12. There are seven differences of systems. Four are the same as with the intervals, which are by magnitude and by genus, and which are consonant and which are rational and irrational. Three are proper differences of systems, which follow: hyperbati, synemmeni, diezeugmeni, immutabilis unchangeable, and intermutabilis interchangeable. Therefore, systems differ in magnitude: larger systems from smaller ones, just as diapason or diapente or diatessaron, or similar ones. The genera are diatonic, enharmonic, or chromatic, or the remaining are chromatic or enharmonic. Consonant and dissonant are those things comprised under consonant sounds from those that are under dissonant ones. There are six consonant things in the immutable system. The smallest is the diatessaron of two and a half tones, as is that which is from hypate hypaton to hypate meson. The second is the diapente of three and a half tones, as is that from proslambanomenos to hypate meson. The third is the diapason of six tones, as is that from proslambanomenos to mese. The fourth is the diapason and diatessaron of eight and a half tones, as is that which is from proslambanomenos to nete synemmenon or paranete diezeugmenon. The fifth is the diapason and diapente of nine and a half tones, as is that which is from proslambanomenos to nete diezeugmenon. The sixth is the disdiapason double octave of twelve tones, as is that from proslambanomenos to nete hyperbolaion. The synemmenon system proceeds to the fourth consonant. For the first is in the diatessaron itself. The second is the diapente. The third is the diapason. The fourth is the diapason and diatessaron. But the place of the voice is increased up to the eighth consonant, which is the disdiapason and diatessaron, and all things that are middle between the stated consonants. There also arise figures of the same magnitude which consist of the same things in composites, and number which do not make an alteration from equal or similar figures. Therefore, there are three species of the diatessaron itself. The first is that which is comprised under the barypycnis deep-dense, which is the 'heavy-dense', as that which is from hypate hypaton to hypate meson. The second is that which is comprised under mesopycnis middle-dense, as is that from parhypate hypaton to hypate meson. The third is that which is comprised under oxypcnis sharp-dense, as is that from lichanos hypaton to lichanos meson. Therefore, in harmony and chroma, the figures of consonants are taken to the habit of dense or thick. But in diatonum, there is no dense. However, that genus is divided into hemitones and tones, and it exists in the diatessaron consonance. One hemitone, two tones. Similarly, also in the diapente, one hemitone, three tones. But in the diapason, two hemitones, five tones. The figures are inspected according to the habit of hemitones. Therefore, there is the first species of the diatessaron itself, whose hemitone is placed in the lower part of the tones. The second, whose first is toward the sharp part. The third, whose middle are the tones. These are similar to the remaining genera from the same sounds to the same ones. There are four figures of the diapente itself: the first comprised under the barypycnis, whose first tone is toward the sharp part.