Much has changed in the eight decades that have passed since Leonard Ellinwood completed his study of Hermann's Musica, and yet much has remained constant. Most of the editions on which he relied for context and loci paralleli have been replaced by editions based on more and better sources. And so the very re-editing of medieval music-theoretical treatises, a process in which Ellinwood's contribution was in the van, has rendered his contribution outdated: this is only in the nature of scholarly progress.

Ellinwood's edition of Hermann's Musica was the third, following Gerbert's of 1784 and Brambach's of 1884, but it was the first to collate the then-newly rediscovered Rochester Codex with Vienna Codex 51, on which alone earlier scholars had relied. Now a third, though fragmentary, source has become available, and it has shed further light on the treatise. Furthermore, musicological efforts in the intervening years have laid a much stronger foundation for understanding Hermann's work and its milieu. Many of the compositions once attributed to Hermann are now known not to be his, and two of his offices (for St. Afra and St. Wolfgang of Ravensburg) have been edited. More of Hermann's astronomical and mathematical writings are available, though some of these still await first editions, and others stand in need of new editions. Our understanding of Hermann's time and place has grown considerably.

Furthermore, the limited distribution of Ellinwood's work has hindered scholarship. His edition is held in relatively few libraries in North America and very few in Europe, to say nothing of its scarcity in the emerging centers of scholarship in Latin America, Asia, and Africa. All too often one finds citations of Hermann that rely on Gerbert, simply because Brambach's and Ellinwood's editions were not available to the author. The time has come, therefore, for an updated edition and revised translation, with a new introduction taking into account the advances of recent decades.

Although much of Ellinwood's work remains useful, it is not without errors and is now seriously outdated. Extensive revision of the translation has resulted in the correction of errors as well as tighter correspondences between Hermann's terminology and the English, closer adherence to Hermann's choice of person and mood, and replacement of some dated language with more modern turns of phrase.