In 1660 Dresden, composer Giovanni Andrea Angelini Bontempi published "Nova quatuor vocibus componendi methodus" (A new method to compose for 4 voices). In it, easy instruction can be found to generate -almost automatically- 4 part polyphony for a given text.
The working principle is incredibly simple: After properly dividing the text into syllables and once establishing a rhythm, the user needs to take "slices" from the wheel (above), each one containing the notes -written numerically, as they will be decoded later. Those notes will then be sung by the four voices indicated on each circle of the wheel: the Bass is the innermost circle, followed by Tenor, Alto, and Soprano (Cantus) as the outermost.
What makes this method unique is that the wheel is designed so that, regardless of the chord sequence, no severe errors occur.
These are the three "modes" the user can choose to convert numbers into notes:
