De institutione musica V.1: Proemium.
After the division of the regular monochord, I think we should add those matters in which the ancient teachers of music disagree through diversity of opinion, and a subtle judgment must be had on all of them. And what is lacking to the work as proposed must be supplied by a moderate exercise of learning. For there can also be another division, in which not one string alone is taken and divided according to the proportions set down, but eight; and such a cithara may be made that, in as many strings as are necessary, the whole reasoning of the proportions is seen as if set before the eyes.