the same period from such a prolific composer and writer, and it is most unusual to be able to work with a medieval composef with such a degree of historical precision and knowledge of repertorial layers.28 'We a.e also fortunate to have copies of Hildegard's music which can be transcribed. The common practice in her region and time was to notate without indicating precise intervals; the music was learned orall¡ with the manuscript notation serving as a guide to memory' But Hildegard's music was newly composed and would have had no earlier tadition to help the singer. Hence it had to be written more precisely if it was to be preserved or transmitted elsewhere. Hildegard's productivity under the fragmented conditions of her life at the tiÃe ,rrr.ly d.p.nded to some degree on the concentrated way in which she thought; she was able to be such a prolific and original composer because of masterful control and use of systems of thought to un- ãerhe all she did. Her work from that turbulent decade-Scll'tias, songs, and play-is dominated by powerful images that become complexes of thoughi and provide organizational frameworks not only for her theology Ùut "lro io. her art works in various media.ze Using the force of any oi the handful of images she particularly favored allowed Hildegard to translate freely from theological writing to drama, to songs, to visual arts. An image clearly beloved by the seer is the Jesse tree, and I will use it, as did she, to organize discussion of her music and its meanings'3o The visual power of the Jesse rree image as it evolved in the twelfth century is *eil known to students of stained glass, of sculpture and, church furniture, and of illuminated manuscripts'3l As she was very much a woman of her times, it should come as no surprise that Hildegard of Bingen was attracted to the complexity and power of the Jesse L". u, u .,r.Ài.I. for explanation. In the first half of the twelfth century the region in which she lived gave birth to the speculwm uirginum (Mirro, o/Virgins), a dialogue written for the education of nuns' The manuscripts ur. fr.qrr.ntly illuminated for pedagogical purposes, and Jesse tree ìmages u.. of central importance in the program; some of the soufces also contain music, written in a style not unlike that of Hildegard.3z The composer, who was constructing her own educational par- ãdig*, may have been directly influenced by this work, as was her cont.rriporury'Herrad of Landsberg, whose Hortus deliciarurn (Garden of Delights), also a work for the education of nuns, featured the Jesse tree ", *.11. The standard scriptural soufce underlying the Jesse tree is Isa- iah fi.t-z,and Isaiah was rhe book of the Bible read during the Advent liturgy in the office. Isaiah rr.r-z was used as the source for several