Breviary / Divine Office / Liturgy of the Hours

All three names refer to the same reality, the official prayer of the Church offered at various times of the day in order to sanctify it. Clergy and religious have a canonical obligation to pray the Liturgy of the Hours as official representatives of the Church. Increasingly, the laity are also praying it, though they do not do so in the name of the Church.

Liturgy of the Hours - From liturgia horarium (L) and the Greek litourgia, a service performed by an official.

Divine Office - From officium divina ( L.), a divine service or duty.

Breviary - From breviarium (L.), a compendium (of the canonical hours). 

The Divine Office is also called the Opus Dei (Work of God).

History

The Divine Office owes its remote origin to the inspiration of the Old Covenant. God commanded the Aaronic priests (c.1280 BC) to offer a morning and evening sacrifice (Ex. 29:38-29). During the Babylonian Exile (587-521 BC), when the Temple did not exist, the synagogue services of Torah readings and psalms and hymns developed as a substitute for the bloody sacrifices of the Temple, a sacrifice of praise. The inspiration to do this may have been fulfillment of David's words, "Seven times a day I praise you" (Ps. 119:164), as well as, "the just man mediates on the law day and night" (Ps. 1:2).

After the people returned to Judea, and the Temple was re-built, the prayer services developed in Babylon for the local assemblies (synagogues) of the people were brought into Temple use, as well. We know that in addition to Morning and Evening Prayer to accompany the sacrifices, there was prayer at the Third, Sixth and Ninth Hours of the day. The Acts of the Apostles notes that Christians continued to pray at these hours (Third: Acts 2:15; Sixth: Acts 10:9; 10: 3, 13). And, although the Apostles no longer shared in the Temple sacrifices—they had its fulfillment in the "breaking of the bread" (the Eucharist)—they continued to frequent the Temple at the customary hours of prayer (Acts 3:1).

Monastic and eremitical (hermit) practice as it developed in the early Church recognized in the Psalms the perfect form of prayer and did not try to improve upon it. The practices were quite individual from monastery to monastery. At first some tried to do the entire Psalter (150 Psalms) each day, but eventually that was abandoned for a weekly cycle built around certain hours of the day. Among the earliest Psalter cycles of which we have a record is the division given by St. Benedict in his Rule ch. 8-19 (c.550), with canonical hours of Lauds (Morning Prayer) offered at sunrise, Prime (1st hour of the day), Terce (3rd hour, or Mid-morning), Sext (6th hour or Midday), None (9th hour or Mid-Afternoon), Vespers (Evening Prayer) offered at sunset,  and Compline (Night Prayer) before going to bed. In addition, the monks arose to read and pray during the Night. This Office of Matins (Readings) likewise had its divisions, into nocturnes, corresponding to the beginning of each of the "watches of the night" (Ps. 63:6), that is, 9 pm, midnight and 3 am. With the reforms of the Second Vatican Council the traditional one-week Psalter cycle became a four-week cycle.

Although the Divine Office has gone through various forms, and reforms, including that of Vatican II, its basic structure, combining Psalms, prayers, canticles and readings, has been relatively constant since the 11th century. Originally the practice of monks, it was also used by the canons of cathedrals and other great churches. The Roman Breviary, perhaps as old or even older than the Benedictine, was originally the Office of the canons of St. Peters and the other Roman Basilicas. Pope Innocent III (1198-1216) extended its use to the Roman Court (curia). When the Franciscan Order was  looking for a convenient one volume Office for its much-traveled friars to use, it adopted this Breviarium Curiae, but  substituting the Gallican (French) Psalter for the Roman. This modified Roman Breviary was then spread throughout Europe by the Franciscans. Pope Nicholas III (c.1270) would then adopt this popularized Franciscan version of the Breviary as the Breviary of Rome itself.

After the Council Trent, and its reforms, the Roman Breviary became the Office of the entire Latin Church. It should be noted that religious orders have a right to their own version, though many simply use the Roman Office. 

Full Versions of the Roman Breviary

Liturgia Horarium, editio typica altera (Libreria Editrice Vaticana, 1985). This is the official Latin text, in 4 volumes, and is lawful throughout the Latin Rite.

Liturgy of the Hours, approved for use in the United States, Canada, South Africa and most English-speaking countries. US edition is published in 4 volumes by Catholic Book Publishing Co, NYC, NY. The 4 volumes correspond to the liturgical seasons (Advent/Christmas, Ordinary Time 1-17, Lent/Easter, Ordinary Time 18-34) and can be purchased individually or as a set.

Divine Office, approved for use in Australia, England, Wales, Ireland and Scotland, Gambia, Ghana, India, Kenya, Liberia, Malaysia, Singapore, new Zealand, Nigeria, Sierra Leone, Tanzania, Uganda and Zimbabwe. Published in 3 volumes by Harper Collins Publishers, London, England.

Abbreviated Versions

Christian Prayer, a one-volume edition of the Liturgy of the Hours (Catholic Book Pub.). This version contains the complete texts of Morning and Evening Prayer for the entire year. It lacks the variety of proper readings and prayers found in the four volume edition. However, it makes a good "starter edition" for the laity, and generally is adequate for following along in community recitation of the Office. There is also a large print edition for the visually impaired.

Shorter Christian Prayer (Catholic Book Pub.) contains Morning and Evening Prayer from the Four-Week Psalter and selected texts for the Seasons and Major Feasts of the year. This is a vademecum (carry with me) for those who only need the basics. There is also a large print edition for the visually impaired.

Shorter Morning and Evening Prayer (Liturgical Press), a vademecum of the Collins Divine Office, approved for use in Australia, England, Wales, Ireland and Scotland, Gambia, Ghana, India, Kenya, Liberia, Malaysia, Singapore, new Zealand, Nigeria, Sierra Leone, Tanzania, Uganda and Zimbabwe.

The first volume of the multi-volume sets contain the norms for the Divine Office called the General Instruction of the Liturgy of the Hours.

General Notes

Psalter. The core of the Office is the 4 week cycle of the Psalter - Sunday Week 1, Monday Week 2,etc., through Saturday Week 4. The Psalter is found in the middle of each volume, dividing the Propers in the front, from the Saints and Commons in the back. 

If you know the liturgical season, and the current week of that season, you can find the Proper and Psalter texts. The following is a typical example.

Friday of the 18th Week in Ordinary Time:

Proper Readings and Prayer - starting from the front of the volume, go to the 18th Week and then Friday of that week.

Psalter - In the Proper, Sunday of the 18th Week will indicate that it is the 2nd week of the Psalter cycle, or calculate yourself. 18/4=4 plus a remainder of 2. It is Week 2 of Psalter.

So, the core of the office is what is given for Friday Week 2 of the Psalter. Around this core is wrapped any special material which accrues to Friday of the 18th week, which can be found in the Proper at the front of the breviary.

The ordinary texts used for all the Offices can be found at the beginning of the Psalter, before Sunday of Week 1.

Saints. 

On a saint's feast day the special prayers and texts are found in the saints' section behind the Psalter. This section is usually the minimum necessary, that is, only what pertains uniquely to that saint. This unique material (e.g. St. Dominic) is then combined with general saint material from the Commons, depending on the category of saint (e.g for Dominic, Common of Pastors, or, Common of Religious).

Guidebooks. 

Finally, for the US, Catholic Book Publishing Company publishes annually the St. Joseph's Guide to the Office for the upcoming liturgical year. It gives the page numbers in the 4 volume Liturgy of the Hours for every part of every office on every day of liturgical calendar. It is highly recommended for novices. They also publish a guide for the one volume condensed version of the Office, Christian Prayer.