"Solica Enchiriadis" and the "Non-Diatonic" Plainsong Tradition
Although medieval plainsong is known as a primarily diatonic repertory, the presence of a "non-diatonic" tradition was brought to light long ago in the work of Gustav Jacobsthal, Dominique Delalande, and others. Some aspects of this practice that have not been fully examined in previous studies are considered, and their relationship to early medieval theory and pedagogy is explored. In the solo verse of the offertory chants, large sections are displaced from the diatonic background scale, sometimes permanently. The conception of irregular semitones presented in "Scolica enchiriadis" yields insight into this extensive "non-diatonic" practice and has implications for interpreting variant readings of these problem spots. Some aspects of the "Enchiriadis" reception that point to changes in tone-system and pitch conception are explored, shedding light on the context surrounding the suppression of irregular semitones.