The Lingua Ignota, "brought forth" by the twelfth-century German nun Hildegard of Bingen, provides 1012 neologisms for praise of Church and new expression of the things of her world. Noting her visionary metaphors, her music, and various medieval linguistic philosophies, Higley examines how the "Unknown Language" makes arid signifiers green again. This text, however, is too often seen in too narrow a context: glossolalia, angelic language, secret...