The beautiful prayer of praise to the Blessed Virgin Mary was written by Saint Ephrem the Syrian, a deacon and doctor of the Church who died in 373. Saint Ephrem is one of the Eastern fathers of the Church most often invoked in support of the dogma of the Immaculate Conception.
O pure and immaculate and likewise blessed Virgin, who art the sinless Mother of thy Son, the mighty Lord of the universe, thou who art inviolate and altogether holy, the hope of the hopeless and sinful, we sing thy praises. We bless thee, as full of every grace, thou who didst bear the God-Man: we all bow low before thee; we invoke thee and implore thine aid. Rescue us, O holy and inviolate Virgin, from every necessity that presses upon us and from all the temptations of the devil. Be our intercessor and advocate at the hour of death and judgement; deliver us from the fire that is not extinguished and from the outer darkness; make us worthy of the glory of thy Son, O dearest and most clement Virgin Mother. Thou indeed art our only hope, most sure and sacred in God's sight, to whom be honor and glory, majesty and dominion, for ever and ever, world without end. Amen.