"Honorius Augustodunensis's Gemma animae, or Jewel of the Soul, stands out among the treatises of the pre-Scholastic blossoming of commentary on the Franco-Roman liturgical rite. Building on the work of Amalar of Metz (775-850), who wrote during the formative stage of this rite, the Jewel is a liturgical encyclopedia, a rhymed-prose summa that explains the sacred mysteries of the Latin Church for clerics. It was read and imitated widely in the twelfth and thirteenth centuries as the major authority on the liturgy, only superseded by William Durand's Rationale divinorum officiorum (1291-1292), a work deeply indebted to it"--