OCTOECHOS. - A liturgical book of the Byzantine rite containing the proper parts of the Divine Office for a series of eight consecutive weeks, arranged according to the progression of the eight musical tones; it is used throughout the liturgical year, except during Lent, Eastertide, and major feasts. There is no study on the history of the O.; its arrangement is attributed to St. John Damascene, but without sufficient foundation. It is perhaps the richest liturgical book.
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**OCTOECHOS** - 16th-century edition (no place or date of printing). Fourth folio with the incipit and illustrations of events from the life of Christ. Copy preserved in the Vatican Library.
ODDO OF CAMBRAI — ODDON OF CLUNY
human nature which expands into individual particularities in each creature (PL 140, 1091). This treatise is an example of the early applications of philosophy to dogma, immediately after the failed attempt of Berengarius of Tours (q.v.).
With the *Disputatio contra Iudaeum de adventu Christi Filii Dei*, O. seeks to convince his adversary solely through logic, presenting a theory of Redemption centered on sacrifice. In the treatise *De blasphemia in Spiritum Sanctum*, he demonstrates that this sin consists in final impenitence. In *De canonis Evangeliorum*, he applies the principles of Eusebius of Caesarea to determine the mutual relationship of the Gospels.
These works have had various editions, the last in PL 140, 1053-1160, where an homily on the *Villicus iniquitatis* is also published, the authenticity of which has been questioned. Other homilies are lost.