All Saints' Day (also called All Hallows or Hallowmas), often shortened to All Saints, is a feast celebrated on November 1 in Western Christianity, and on the first Sunday after Pentecost in Eastern Christianity in honour of all the saints, known and unknown.In terms of Western Christian theology, the feast commemorates all those who have attained the beatific vision in heaven. Specifically, in the Roman Catholic Church, the next day, All Souls' Day, commemorates the departed faithful who have not yet been purified and reached heaven
Among Eastern Orthodox and Eastern Catholics, All Saints Sunday (Greek: Αγίων Πάντων, Agiōn Pantōn), follows the ancient tradition of commemorating all saints collectively on 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 "the Wise" (886–911). His wife, Empress Theophano—commemorated on December 16—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 righteous, she would also be honored 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.
