The Great Paschal Cycle with Commentaries and Order by Tbel Abuserisdze (1190–1240) places him at the forefront of Georgian astronomical and mathematical sciences. The main objects of his scientific interest in the work are the Great Paschal Cycle and the ecclesiastical calendar as the basis of orthological and liturgical practices. The Great Paschal Cycle with Commentaries and Order is devoted to the great indication (532-year cycle), calendar features, and chronological questions. The text answers the question why the fasts of Greeks and Georgians coincide, while the Greek calendar is 96 years behind Georgian (Greeks count 5508 BC, and Georgians – 5604).