In 451, during the reign of the Sovereigns Marcian and Pulcheria, the Fourth Ecumenical Council was convoked in Chalcedon against Eutyches and those of like mind with him. After much debate, the Fathers who were the defenders of Orthodoxy, being 630 in number, agreed among themselves and with those who were of contrary mind, to write their respective definitions of faith in separate books, and to ask God to confirm the truth in this matter. When they had prepared these texts, they placed the two tomes in the case that held Saint Euphemia's relics, sealed it, and departed. After three days of night-long supplications, they opened the reliquary in the presence of the Emperor, and found the tome of the heretics under the feet of the Martyr, and that of the Orthodox in her right hand. (For her life, see Sept. 16.)

Saint Olga, renowned for her wisdom and sobriety, in her youth became the wife of Igor, Great Prince of Kiev, who ruled during the tenth century. After her husband's death, she herself ruled capably, and was finally moved to accept the Faith of Christ. She traveled to Constantinople to receive Holy Baptism. The Emperor, seeing her outward beauty and inward greatness, asked her to marry him. She said she could not do this before she was baptized; she furthermore asked him to be her Godfather at the font, which he agreed to do. After she was baptized (receiving the name of Helen), the Emperor repeated his proposal of marriage. She answered that now he was her father, through holy Baptism, and that not even among the heathen was it heard of a man marrying his daughter. Gracefully accepting to be outwitted by her, he sent her back to her land with priests and sacred texts and holy icons. Although her son Svyatoslav remained a pagan, she planted the seed of faith in her grandson Vladimir (see July 15). She reposed in peace in 969.

It is believed that the Synaxis of the Archangel Gabriel was transferred to this day from March 26 so that it could be celebrated more festively than in the period of the Great Fast; and, in fact, all the miracles of the Archangel are celebrated on this feast day, which has been listed here in the church books since the ninth century.

Grandson of Saint Olga, Saint Vladimir ascended the throne of Kiev in 980. Though a zealous idolater, he was illumined by the grace of God, accepted the Christian Faith, and completely changed his ways. He was baptized in Cherson in 988, receiving the name Basil; he came forth from the font not only healed of a blindness lately afflicting him, but also from being passionate and warlike, he became meek, peaceable, and exceedingly godly. Whereas his grandmother had refused marriage with the Emperor in Constantinople (see July 11), he married Anna, sister of the Emperors Basil and Constantine, and was accompanied home by priests from Constantinople. Diligently seeking to spread Christianity throughout his realm like a new Constantine, he destroyed the idols (having the chief diety Perun scourged and then cast into the Dnieper River), and summoned all his subjects to Holy Baptism. He reposed in peace in 1015.

On the Sunday that falls from the 13th to the 19th of the present month, we chant the Service to the Holy and God-bearing Fathers who came together in the Seven Ecumenical Councils, that is: the First Council, of the 318 Fathers who assembled in Nicaea in 325 to condemn Arius, who denied that the Son of God is consubstantial with the Father; the Fathers of the First Council also ordained that the whole Church should celebrate Pascha according to the same reckoning; the Second Council, of the 150 Fathers who assembled in Constantinople in 381 to condemn Macedonius, Patriarch of Constantinople, who denied the Divinity of the Holy Spirit; the Third Council, of the 200 Fathers who assembled in Ephesus in 431, to condemn Nestorius, Patriarch of Constantinople, who called Christ a mere man and not God incarnate; the Fourth Council, of the 630 who assembled in Chalcedon in 451, to condemn Eutyches, who taught that there was only one nature, the divine, in Christ after the Incarnation, and Dioscorus, Patriarch of Alexandria, who illegally received Eutyches back into communion and deposed Saint Flavian, Patriarch of Constantinople, who had excommunicated Eutyches; the Fifth Council in 553, of the 165 who assembled in Constantinople for the second time to condemn Origen and Theodore of Mopsuestia, the teacher of Nestorius; the Sixth Council in 680, of the 170 who assembled in Constantinople for the third time, to condemn the Monothelite heresy, which taught that there is in Christ but one will, the divine; and the Seventh Council in 787, of the 350 who assembled in Nicaea for the second time to condemn Iconoclasm.