The classic exploration of Syriac liturgical melodies, the work of Dom Jeannin has no rivals. Beginning with a discussion of the nature of Beth Gazo, the treasury of chants, this work provides a careful introduction to the various types of liturgical music found in the church. Homilies in strophic form, the popular poetry of the fifth-century qole, St. Ephrem's mudrosho, antiphonal psalms, anthems (mawrbe), the Greek Canon, melismatic hymns or litanies, and melodies from Mosul are all part of the service music and hymnody discussed in the introduction and presented with their melodies in Syriac. This scarce source contains a wealth of information on Syriac liturgical practice and its accompanying music.

Jules Cécilien Jeannin was a priest of the Benedictine order. Noted as a musician as well as a musicologist, he was an authority on Syrian chant. Associated with the abbey of Hautacombe, he made lasting contributions to the study of Gregorian Chant for which he is still cited.