This 10th-century version of Boethius’ De institutione musica (commonly known as De musica) is the Library's oldest book. Originally written by Boethius in the fifth century, the book shaped European music for seven centuries. At one time it was the most-copied musical text and Boethius came to be viewed as a primary authority on Greek musical thought.
Rather than commenting on the practice of music, De musica consists primarily of definitions and explanations of musical terms in relation to mathematics. This approach, which considered music as a mathematical discipline, was prevalent among scholars up to the Middles Ages.
Anicius Manilus Severinus Boethius (c480–c525) was born in or near Rome to a politically prominent family. His life was primarily that of a scholar, but because of his family he couldn't avoid politics. When in his forties, he became tutor to the Gothic king Theodoric, until the latter had him imprisoned on suspicion of treason and, a year later, Boethius was executed.
It was while in prison that Boethius wrote the tome for which he is best remembered, The consolations of philosophy. De musica, however, was one of a series of texts written as a young man. A translation of the musical writings of the Greek philosopher Nicomachus, it's one of a series of texts on what were then thought to be the four mathematical disciplines: music, arithmetic, astronomy and geometry. Of Boethius' four texts, only those on music and arithmetic survive.
Of the 137 manuscripts or fragments of De musica which have survived, the Library's copy is one of the earliest. It is a working manuscript, with very few illustrations and numerous additions and corrections to the text.
Attached to this work is an abridged version of Musica enchiriadis. Often bound with De musica, it is an anonymous 9th-century musical treatise documenting both the practical and theoretical aspects of music practice at this time.