Author: Doni, Giovanni Battista - manuscripts of italian music theory ...

chiarascuro, as it is called, which is the same as calling it light and shadow, in the
same way one cannot create a melody without this combination of intervals large and
small which in the Diatonic and natural genus are the tones and the Semitones. This
simile is so appropriate to express this propriety of music that the ancient painters, as
Pliny teaches us, used this word of tone to denote that part of the colour which is
[[that]] midway between light and dark. And one sees that it is established by nature
with admirable order (which it is found in excellence in every part of music) that just
as the first division of the octave is made into a fifth and a fourth (which almost as a
perfect union of male and female form the matrimony of Harmony which contains
everything, namely the eighth Diapason, to which [[is given this]] [--] one of the
meanings of the word Harmony corresponds, thus also the progress of any song and
melody is created with the same components of fourth and fifths placed in alternation.
Because [[the octave]] the Diapente spans a whole Diatessaron and a tone (always
intending, unless stated otherwise the sesquiottavo and larger which was the only one
know in the most ancient times) and, consequently, the Diapente embraces two
Diatessara and a Tone, it was rightly called the tone of the disjunction or division to
distinguish it from the others which are put as integral parts of the two Diatessara.
This was done because it separates at the same time the same fourths [[albeit it
unites]] and unites them within the consonance of an octave. Now, we understand that
this separation occurs when an intervals is interposed between two others, which do
not have a common term, but each one has its own, as from one can see in these
examples
[Doni, On the Genera and the Modes, 20]
In the first of them the note a la mi re unites two fourths, since it is a common term
between both of them, so that the two extreme sound a seventh. In the second then
the tone which intervenes between a la mi re and [sqb] mi separates and divides the
two fourths, namely, the lower one E A, and the higher one [sqb] e, so that their
highest and lowest notes answer each other [--] at the distance of an octave.
Therefore, it follows that, since the ancients found this order perfectly, one sees in any
kind of melody that nature abhors to continue for more than three tones because of the
great harshness that they would create and the juxtaposition of two Semitones. This in
nature does not happen, because, equally nature refuses that subtle tenderness which
they caused. The ancient established their large Diatonic System on two octaves
[[and]] and, consequently, on two fifths and two fourths, and they gave the same
name [names ante corr.] to [[the notes]] each note which has the note that sounds that
sound. Therefore one must imagine that this system is nothing else but a disposition
of fifteen strings in an instrument which would have been so disposed according to
the adjacent intervals which are sung in the Diatonic. Therefore, they divided all the
large System into four Tetrachords (namely four smaller systems of four strings or
notes each) and two Tones which are used for the mention Disjunction and for the
creation of the fifths and the completion of the octaves. However, one must note
already that, albeit [[in their authors what sort]] the modern authors commonly
maintain that [[Salinas Zarlino in the second part of the Institutioni musicali chapter
50 in marg.]] our Scale or perfect System is divided in hexachords because of the
choice of those six notes Ut Re mi fa sol la and then they contrast and compare those
hexachords with the ancient Tetrachords [--] as Salinas does apart from Zarlino