Having spoken of the tuning of the harpsichord and the organ and having demonstrated how it is perfect in its intervals, all of them uniform in their nature, it must be understood that organists must never transpose either the tons of the church or the modes of music except to the customary notes or keys. Choirmasters must not and cannot force them to do otherwise (though organists should know how to transpose to any note, in order to show that they are able to do so). Because in transposing the first [ton] to E mi, la, it must be admitted that the final cadence is worthless, as it is made on a minor semitone. The major third of that cadence is also worthless, being larger than a major third. The major third is made up of two whole and equal tones, while the superfluous third is made up of a major tone and a superfluous tone. It is consequently too wide and is worthless, as is the cadential trill.

The organist must under no circumstances transpose to or play in that ton, nor in the second [ton] on F ut, fa, because the minor third, composed of a major tone and a minor semitone, is too narrow and is worthless, and because a superfluous tone must be employed, playing re [on] F ut, fa; mi on G re, sol, ut; fa as the feinte of G re, sol, ut, which is the worthless minor semitone; sol on B fa, which is the superfluous tone; and la [on] C sol, ut, fa.