The music theory booklet Balliol 173A, fols. 74r–81v: scribal organisation of an early medieval theory miscellany

Abstract Using evidence of the quality of vellum, fascicle structure, scribal hands and illustrations, this article argues that the first fascicle of the music portion of Oxford, Balliol College, 173A (fols. 74–81) is a self-standing booklet, perhaps created to teach a scribe the basics of music theory and how to arrange text while leaving space for illustrations or examples. A new fascicle structure of the gathering is proposed that accounts for a previously unrecognised missing folio. An analysis of the contents of the gathering demonstrates that the theory booklet is a compilatio , with portions of the Musica disciplina (or it sources) acting as a frame to start and end the booklet, with other works (Pseudo-Jerome, Isidore of Seville and Cassiodorus) inserted in between. The final folios are completed with a number of small tractatuli , including the brief dialogue Diapason quid est? The contents of both the booklet and the entire music codex are closely paralleled in one of the smaller manuscripts collected into Oxford, St John's College 188 and also Cambridge, Trinity College R.15.22. While it will be ever easier to study digital images of manuscripts and to create critical editions of well-defined texts, this article argues for the continuing importance of codicological study of manuscripts in situ to coordinate the placements of texts within the structure of codices.