The Horologion (Greek: ῾Ωρολόγιον; Church Slavonic: Часocлoвъ, Chasoslov, ), or Book of Hours, provides the fixed portions of the Daily Cycle of services (Greek: akolouthies, Template:Polytonic) as used by the Orthodox Church. Into this fixed framework, numerous moveable parts of the services are inserted.
Several varieties of Horologia exist, the most complete of which is the Great Horologion (Greek: ῾Ωρολόγιον τò μέγα, Horologion to mega; Slavonic: Великий Часословъ, Velikij Chasoslov). It contains the fixed portions of the Daily Cycle of Services, (Vespers, Compline (Great and Small), Midnight Office, Matins, the Hours, the Inter-Hours, Typika, Prayers before Meals). The parts for the Reader and Chanters are given in full, the Priest's and Deacon's parts are abbreviated. The Great Horologion will also contain a list of Saints commemorated throughout the year (with their Troparia and Kontakia), selected propers for Sundays, and moveable Feasts (from the Triodion and Pentecostarion), and various Canons and other devotional services. The Great Horologion is most commonly used in Greek-speaking churches.
Various editions of the Horologion are usually shorter; still giving the fixed portions of the Daily Office in full, but with the other texts much more abbreviated (all of which are found in full in the other liturgical books). In addition, such texts often also contain Morning and Evening Prayers, the Order of Preparation for Holy Communion, and Prayers to be said after receiving Holy Communion.
- Horologion For use at Reader's services (i.e., when a priest is not serving)
- Horologion Texts in Word Format
- Practical Tips on how to build a Liturgical Library
- Photo of monks reading the Divine Office Church of the Holy Sepulchre, Jerusalem