Even Patrick’s great prayer in Irish – sometimes called “Saint Patrick’s Breastplate” because it was thought to protect him from hostile powers, sometimes called “The Deer’s Cry” because it was thought to make him resemble a deer to the eyes of those seeking to do him harm – cannot be definitely ascribed to him. Characteristics of its language would assign it to the seventh, or even to the eighth, century. On the other hand, it is Patrician to its core, the first ringing assertion that the universe itself is the Great Sacrament, magically designed by its loving Creator to bless and succor human beings. The earliest expression of European vernacular poetry, it is, in attitude, the work of a Christian druid, a man of both faith and magic. Its feeling is entirely un-Augustinian; but it is this feeling that will go on to animate the best poetry of the Middle Ages. If Patrick did not write it (at least in its current form), it surely takes its inspiration from him. For in this cosmic incantation, the inarticulate outcast who wept for slaves, aided common men in difficulty, and loved sunrise and sea at last finds his voice. Appropriately, it is an Irish voice.Cahill, How the Irish Saved Civilization, p. 116
Read St. Patrick’s Breastplate here.