|The Feast of All Saints|
All Saints' Day, though not one of the twelve Great Feasts of the Church year, is a significant feast day on which all saints (both known and unknown) are commemorated collectively on the first Sunday after Pentecost.
St Ephrem the Syrian (d. 373) mentions a Feast dedicated to the saints in his writings. St John Chrysostom (d. 407) was the first Christian we know of to assign the Feast to a particular day: the first Sunday after Pentecost. The feast of All Saints achieved great prominence in the ninth century, in the reign of the Byzantine Emperor, Leo VI (886-911). His wife, Empress Theophano lived a devout life. After her death, her husband built a church, intending to dedicate it to her. When he was forbidden to do so, he decided to dedicate it to "All Saints," so that if his wife were in fact one of the saints, she would also be honoured whenever the feast was celebrated. According to tradition, it was Leo who expanded the feast from a commemoration of All Martyrs to a general commemoration of All Saints, whether martyrs or not.
The Sunday following All Saints' Sunday - the second Sunday after Pentecost - is set aside as a commemoration of all locally venerated saints, such as 'All Saints of Britain' or 'All Saints of Mount Athos'. The third Sunday after Pentecost may be observed for even more localized saints, such as "All Saints of London", or for saints of a particular type, such as "New Martyrs of the Turkish Yoke."
With the Feast of All Saints, the season of the Pentecostarion (from Easter through Pentecost to All Saints' Day) comes to an end.