St. Irenaeus, born at Smyrna in Asia Minor, was a pupil of the Martyr St. Polycarp, Bishop of that city, and himself a favorite disciple of St. John the Evangelist. Later he became Bishop of Lyons in Gaul, where, with many other Christians, he was put to death for the Faith , 202. In his writings, many of which are still extant, St. Irenaeus bears eloquent testimony to the primary in the Church of St. Peter’s See.
The origin of this feast is similar to that of the Blessed Sacrament. The symbolism surrounding the wound in the side of Jesus made by the lance of Longinus, from which flowed blood and water, was already familiar to the early Fathers of the Church. There are wonderful pages in the writings of St. Augustine and St. John Crysostom about the Church which, radiant with youth, springs from the side of the new Adam asleep upon the cross, as well as about the divine sacraments which flowed from the loving Heart of the Redeemer.