Anicius Manlius Severinus Boethius
Fundamentals of Music
translated with an introduction by Calvin M. Bower
Yale University Press, 1989
In medieval times, there was only one book about music of any importance - the treatise "De Institutione Musica" by the 5th century scholar Boethius. This latin text was extremely influential right doen to the 17th century, and was certainly known to musicians and scholars in Britain and Ireland all through the medieval period. Many aspects of our early Gaelic music may be related to or derived from this text. The treatise summarises and digests the classical music theory of the ancient Greeks. Though the latin text is easily available online, there has only ever been one English translation, by Calvin Bower, with a very interesting introduction. Published by Yale University Press in 1989, and never reprinted. Copies are exceedingly hard to find now.