Abstract
<jats:p>The events of Jesus’ Crucifixion and his Resurrection three days later provide the basis for Christians’ belief in redemption and an existence after death. Consequently, the celebration of the events of Jesus’ Passion represents the most important feast in the Christian calendar, designated Pasch, or Easter in English. The four Gospels correlate the Crucifixion with the Jewish feast of Passover, celebrated at the time of the spring full moon, so initially the Passover full moon determined the approximate date of the Christian celebration. However, as Christianity spread beyond Palestine it became difficult for the dispersed Christian communities to synchronize their celebration of Pasch. In AD 269, Anatolius, bishop of Laodicea in modern Syria, established an accurate 19-year lunar cycle to predict the date of the spring full moon for future years. In circa AD 309, Eusebius, bishop of Caesarea, used Anatolius’ 19-year lunar cycle to construct a table to schedule Pasch for the future years. In AD 328 Athanasius, bishop of Alexandria, modified Anatolius’ lunar cycle by advancing all nineteen full-moon dates by exactly two days, and this cycle was continued by his episcopal successor, Theophilus. In circa AD 412 the Alexandrian mathematician, Annianus, further modified this cycle by advancing its saltus by three years. Annianus’ cycle was quickly adopted by Theophilus’ episcopal successor, Cyril, who misrepresented that Annianus’ cycle had been authorized by the Council of Nicaea. This was the cycle that prevailed in the Western Church until Pope Gregory reformed the calendar in 1582, and this book comprehensively documents for the first time the evolution of these Paschal cycles.</jats:p>