Long recognized as one of the most important medieval treatises on music, the Musica of Hermannus Contractus is here presented in a newly revised translation, with commentary reflecting the best current scholarship. A polymath and monk, Hermannus Contractus (1013-54) contributed to the important advancements made in European arts and sciences in the first half of the eleventh century, writing on history, astronomy, and time-keeping devices, among other topics, and composing several chants. His music theory, founded on a systematic treatment of traditional concepts and terminology dating back...