The Trisagion Hymn (English and Greek)

"The hymn is of great antiquity, and perhaps much older than the event assigned by the Greek Menology as connected to its origin. The tradition recounts that during the reign of Theodosius II (408-450) Constantinople was shaken by a violent earthquake, and that whilst the people, the emperor and the Patriarch Proclus of Constantinople (434-446) were praying for heavenly assistance, a child was suddenly lifted into midair, to whom all cried out Kyrie eleison ('Lord, have mercy'). The child was then seen to descend again to the earth, and in a loud voice he exhorted the people to pray : 'Holy God, Holy Mighty, Holy Immortal'."