A faint outline of a left hand, likely a Guidonian hand (manus Guidoniana), is visible across the page. This was a central mnemonic device in the history of Western music theory, used for centuries to teach singers how to navigate the "gamut" or range of musical notes by mapping them to the joints and fingertips of the hand.

Chapter Five

A clear demonstration of the errors of certain people regarding the aforementioned matters.

Although not everything set forth by him Likely referring to a specific theorist or the previous chapter's subject concerning these matters has been published by us, I do not think the reader should judge that we have done so recklessly. Indeed, if God favors our prayers and efforts, every necessary point—even those which are placed in a disorganized and confused manner by him and others—will be addressed in its proper place, and not a single iota shall be left untouched. Furthermore, we shall soon point out other matters which they understood poorly and in which they were deceived by error.

It was stated above and demonstrated that the synemenon tetrachord original: "tetracordum synemenon." In the Greek system, this is the "conjunct" group of four notes that introduces the B-flat. is joined to the diazeugmenon The "disjunct" tetrachord, which uses B-natural. or is separated from it. However, some who are ignorant of these things—as we investigated in a long dispute with our very close friend Tristan de Silva, a Spaniard and a man of the sharpest intellect—place the disjunct tetrachord when they reach the mese The "middle note" of the Greek system, equivalent to A.. After this, they place the synemenon, then the hypoboleon The "extra" notes added to the top of the scale., and thus they cause the nete hyperboleon The highest note of the standard Greek system. to be distant from the proslambanomenos The lowest note of the system. by three strings beyond two octaves original: "diapason.". It is manifest that this is against the truth and the teaching of Boethius An influential 6th-century philosopher whose "De institutione musica" was the standard textbook for medieval music theory..

Boethius himself declares this most accurately in the first book, in the chapter beginning "But since he places the middle note again," and it is further declared evidently with numbers and a measured diagram in the fourth book, in the chapter beginning "The two tetrachords which are joined to each other, but disjoined from the middle note." But regarding these matters, we have written in our Theoretica The author's own theoretical work.; nor would I have cited anything here except to show the error of many regarding this, as many of these people easily follow these teachings in their own learning.

Marchetto Marchetto da Padova (fl. 1305–1319), a hugely influential Italian theorist who updated the system of notation and measurement., however, does not do it this way; rather, he places the disjunction from the mese. After that, he places the hyperboleon, then the synemenon, and thus he arranges eighteen strings. To these, he adds one below (namely gamma) and another above (namely e), increasing the number to twenty strings. But if anyone wishes to understand him in a healthy way, they could, in my judgment, say that once that synemenon tetrachord is removed, the remaining notes are arranged in that manner. Then, after the nete hyperboleon, since it is similar to the mese, the synemenon tetrachord is placed in the way it ought to follow after the mese; and so as not to hinder the diazeugmenon, he arranged it thus. It could be saved In a logical or theological sense: to "save" an argument is to find a way to make it consistent with the truth. in many other ways as well. I, for my part, do not doubt that he is "saved," since Christ on the cross prayed for those who know not what they do.

A certain brother, Johannes of the Carthusian Order, a Frenchman, tries to "save" him by calling him both unlearned and in need of the schoolmaster's rod. For my part, I value this Marchetto as much as four Marchettos. This is likely a pun or a bit of academic sarcasm regarding Marchetto's status and the Carthusian's defense of him.