Practica Musicae utriusque cantus, excellentis Franchini Gaffori Laudensis quatuor libris modulatissima

...in the acute interval, they placed the letter C and the syllable fa. For I understand an interval or space as an empty margin interjected between two lines by acuteness and gravity. And with a similar progression, they annotated the letters themselves and the seven syllables of the hexachords on the little strings; but many things regarding these places might be sought here, which, since they have been clearly deduced in the fifth book of Theory, we have decided to pass over in silence for the sake of brevity. And let the diatonic introductory of Guido, with letters and syllables described by lines and spaces, be arranged in this paragraph.

A large, faint, vertically-oriented diagram shows a musical staff or gamut structure with vertical lines and annotations, partially obscured by the bleed-through of text from the verso side of the page.