→Kathismata: grammar, missing word
The Psalter is divided into 20 '''kathismata'''. Each '''kathisma''' is further divided into three ''stases''. Each ''stasis'' contains between one and three chapters. The exception to this is Psalm 118. Due to its great length, this chapter constitutes the entire XVIIth Kathisma.
Each of the divine services
contain fixed portions of the Psalter that are read or chanted each time the service is celebrated. In addition, certain services of the Daily Cycle contain prescribed kathisma readings. These prescribed readings rotate daily so that outside of Great Lent the Psalter is read through once in its entirety in single week.
During the lenten fast, the kathisma readings are accelerated so that the Psalter is read through in its entirety twice each week.