Orthodox icon of Synaxis of All the Saints.
Comemmorated Sunday after Pentecost.
The Sunday following Pentecost is dedicated to All Saints, both those who are known to us, and those who are known only to God. This feast may have originated at an early date, perhaps as a celebration of all martyrs, then it was broadened to include all men and women who had borne witness to Christ by their virtuous lives, even if they did not shed their blood for Him. The feast of All Saints achieved great prominence in the ninth century, in the reign of the Byzantine Emperor Leo VI the Wise (886-911).
His wife, the Holy Empress Theophano (December 16) lived in the world, but was not attached to worldly things. She was a great benefactor to the poor, and was generous to the monasteries. She was a true mother to her subjects, caring for widows and orphans, and consoling the sorrowful. Even before the death of St Theophano in 893 or 894, her husband started to build a church, intending to dedicate it to Theophano, but she forbade him to do so.
It was this emperor who decreed that the Sunday after Pentecost be dedicated to All Saints. Believing that his wife was one of the righteous, he knew that she would also be honored whenever the Feast of All Saints was celebrated.