The Feast of the Life-giving Spring which is kept on the Friday of Bright Week has its origins in the 5th century. It is the feast that commemorates the consecration of the Church of the Life-giving Spring outside of Constantinople.
The very large and beautiful church named in honor of the Theotokos of the Life-giving Spring was built about the middle of the fifth century by the Emperor Leo the Great (457-474 AD), outside of Constantinople. Emperor Leo was a pious man (he is commemorated on January 20th) and before he became Emperor, he had encountered a blind man, who being tormented with thirst asked him to help him find water. Leo felt compassion for him and went in search of a source of water, but found none. As he was about to cease his search, he heard a voice telling him there was water nearby. He looked again, and found none. Then he heard the voice again, this time calling him "Emperor" and telling him that he would find muddy water in the densely wooded place nearby; he was to take some water and anoint the blind man's eyes with it. When he had done this, the blind man received his sight.
After Leo became Emperor, as the Most Holy Theotokos had prophesied, he raised up a church temple over the spring, whose waters worked many healings, as well as resurrections from the dead, through the intercessions of the Theotokos. From this, it came to be called the "Life-giving Spring."