During the Great Fast, a special service book is used, known as the Lenten Triodion, which contains the Lenten texts for the Daily Office (Canonical Hours) and Liturgies. The Triodion begins during the Pre-Lenten period to supplement or replace portions of the regular services. This replacement begins gradually, initially affecting only the Epistle and Gospel readings, and gradually increases until Holy Week when it entirely replaces all other liturgical material. During the Triduum even the Psalter is eliminated, and all texts are taken exclusively from the Triodion. The Triodion is used until the lights are extinguished before midnight at the Paschal Vigil, at which time it is replaced by the Pentecostarion, which begins by replacing the normal services entirely (during Bright Week) and gradually diminishes until the normal services resume following the Afterfeast of Pentecost.
During the Great Fast a special service book is used known as the Lenten Triodion which contains the Lenten texts for the Daily Office (Canonical Hours) and Liturgies The Triodion begins during the Pre-Lenten period to supplement or replace portions of the regular services This replacement begins gradually initially affecting only the Epistle and Gospel readings and gradually increases until Holy Week when it entirely replaces all other liturgical material During the Triduum even the Psalter is eliminated and all texts are taken exclusively from the Triodion The Triodion is used until the lights are extinguished before midnight at the Paschal Vigil at which time it is replaced by the Pentecostarion which begins by replacing the normal services entirely (during Bright Week) and gradually diminishes until the normal services resume following the Afterfeast of Pentecost