Florentius de Faxolis was a musician in the service of Cardinal Ascanio Maria Sforza in Naples and Rome in 1481–82. He was appointed canon of San Fiorenzo at Fiorenzuola d'Arda in 1482 and became a priest in 1484. His Liber musices, preserved in a lavishly illuminated parchment manuscript in the Biblioteca Trivulziana in Milan, was written at the cardinal's request between 1485 and 1492. The identity of the author with the canon of the same name has recently been questioned (Francesco Rocco Rossi, “Auctores in opusculo introducti: l'enigmatico Florentius musicus e gli sconosciuti referenti teorici del Liber Musices (I-Mt 2146),” Acta Musicologica 80.2 [2008]: 165–77), but the editors of this edition argue convincingly that they are the same individual.

Florentius's purpose was not to present original ideas about his subject, but to compile the information on music that would be useful to his patron, an aristocrat with a humanistic education and an avid amateur musician. The value of the book for modern readers lies in the light that it casts on the concept of music as a liberal art in the culture of late fifteenth-century humanism. Florentius draws on an impressive array of authorities, including classical writers, church fathers, and medieval scholars, as well as music theorists from ancient times to the recent past. His most important fifteenth-century source is a music treatise by the monk, philosopher, and theologian Blasius Romerus that is no longer extant, but that can be partially reconstructed from Florentius's text. Unlike most music theorists of the time, Florentius identifies his sources explicitly and quotes extensively from them, perhaps to display his erudition or to provide information about the sources to the dedicatee. Some of his chapters consist of little more than anthologies of quotations from earlier authorities. The subjects that he discusses are conventional and organized in the usual way. Book 1 covers the praises, definition, origin, and classification of music and topics relating to pitch and plainchant; book 2 deals with counterpoint and composition and book 3 with mensuration and proportions. Because of the purpose of the work, the coverage of the non-technical topics discussed by classical and medieval authors is more extensive than it is in most writings on music.

Florentius was not a deep or critical thinker. Most of the information he transmits is explained competently, but when he tackles complex issues, he sometimes gets in over his head. The organization of topics is not always systematic, and the explanations of principles are at times incomplete, ambiguous, or incorrect. Despite these deficiencies, the book includes interesting comments on a few topics, such as a method for using the words of a song to help a singer recall the melody, that are not discussed by other theorists.

This edition and translation, the work of a musicologist (Bonnie J. Blackburn) and a classical scholar (Leofranc Holford-Strevens), provides much more than an expert text and translation of Florentius's book. It includes a historical introduction with new insights about the author's identity and copious notes and commentary on the text. The editors provide precise identifications of Florentius's sources, including the ones he neglects to name or identifies incorrectly; where necessary, they discuss different versions of the quoted texts in other sources and problems regarding their wording and meaning. The edition is therefore a valuable source of information on commonly cited statements about music in classical and medieval writings even for readers who have no interest in Florentius himself. Issues that require more extensive discussion are treated in a separate commentary. Every ambiguous, unconventional, or erroneous statement in Florentius's book is subjected to close analysis and explained clearly. The editors supply musical examples for Florentius's rules of counterpoint where they not given by the author, and they provide a detailed analysis of his use of Latin, which, like the ideas in his book, turns out to be a curious mixture of classical, unclassical, and incompetent elements.

The editors’ book is much more than an edition of an interesting fifteenth-century source; it is an important study in its own right of the musical culture of the late fifteenth century. It brings to life a fascinating document that demonstrates the centrality of music, from its mythological and mathematical foundations to its technical fine points, in the intellectual and artistic life of its time.