Overview
In western Catholicism, canonical hours may also be called offices, since they refer to the official set of prayer of the Roman Catholic Church that is known variously as the Divine Office (from the Latin officium divinum meaning "divine service" or "divine duty"), and the Opus Dei (meaning in Latin, "Work of God"). The current official version of the hours in the Latin Rite of the Roman Catholic Church is called the Liturgy of the Hours (Latin: Liturgia horarum) in North America or Divine Office in the British Isles. Historically, it was also the only set of hours in which couples could be legally wed in the Anglican Church.
In the Anglican tradition, they are often known as the Daily Office or Divine Office, to distinguish them from the other Offices of the Church.
In the Orthodox Church, the canonical hours may be referred to as the "Divine Services", and the Book of Hours is called the Horologion (Greek: ῾Ωρολόγιον). There are numerous small differences in practice according to local custom; but the overall order is the same among Byzantine Rite monasteries, although parish and cathedral customs vary rather more so by locale.
The usage among the Oriental Orthodox Churches and the Assyrian Church of the East and of their Eastern Catholic all differ from each other and from other rites.
The practice of daily prayers grew from the Jewish practice of reciting prayers at set times of the day: for example, in the Book of Acts, Peter and John visit the Temple for the afternoon prayers (Acts 3:1). Psalm 119:164 states: "Seven times a day I praise you for your righteous laws" which is among the scriptural quotes in the attestation of Saint Symeon of Thessaloniki that commences "The times of prayer and the services are seven in number, like the number of gifts of the Spirit, since the holy prayers are from the Spirit."
This practice is believed to have been passed down through the centuries from the Apostles, with different practices developing in different places. As monasticism spread, the practice of specified hours and liturgical formats began to develop and become standardized. Around the year 484, Sabbas began the process of recording the liturgical practices around Jerusalem while the cathedral and parish rites in the Patriarchate of Constantinople evolved in an entirely different manner; the two were synthesized commencing in the eighth century to yield an office of great complexity. In 525, Benedict of Nursia wrote the first official western manual for praying the Hours. With the Cluniac reforms of the 11th century there was a new emphasis on liturgy and the canonical hours in the reformed Benedictine priories with the Abbey of Cluny at their head. The Holy See did not issue an official Roman breviary until the 11th century, as part of the reforms that were designed to bring all the variant usages of Christian churches in the West into conformity.
Already well-established by the ninth century in the West, these canonical offices consisted of eight daily prayer events and three (or four) nightly divisions (called "nocturns", "watches," or "vigils"). Building on the recitation of psalms and canticles from scripture, the Church has added (and, at times, subtracted) hymns, hagiographical readings, and other prayers.
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