The feast of Corpus Christi which we celebrate today is popularly said to have begun with a Bohemian priest named Peter, who was suffering from grave doubts about the doctrine of transubstantiation and the Real Presence of Christ in the Eucharist. While on pilgrimage to Rome, he celebrated Mass at the town of Bolsena, and the host in his hand turned for a moment into actual flesh, correcting his belief. He then brought the blood-stained corporal to Pope Urban IV (1261-64), who was living in the nearby city of Orvieto at the time (as the Popes often did in the Middle Ages), and in celebration of the miracle, the Pope ordered a new feast to be instituted.
As much as one dislikes to impugn such a legend, it rests on highly dubious historical grounds, being unheard of before the middle of the following century. The feast’s true origin lies rather with a different miracle. Starting at the age of sixteen, a woman named Juliana (1192 – 1258) from the city of Liège frequently had a vision of the moon with a dark spot or streak on it. Christ Himself eventually revealed to her its meaning, that the moon represented the Church’s liturgical year, and the spot represented the lack of a special feast to celebrate the mystery of the Eucharist.
Juliana, of course, had no way of instituting such a feast on her own. However, in 1225, she was elected prioress of the monastery she had entered, which gave her the position to speak to the learned men of the region. They determined that such a feast could and should indeed be instituted, and it was celebrated for the first time in the church of St Martin in Liège in 1246. Many scholars believe that the original form of its Divine Office was composed by Juliana herself, whom the Church now recognizes as a Saint.
(The Vision of St Juliana, ca. 1645, by Philippe de Champagne)
Three years after her death, the former archdeacon of Liège, Jacques Pantaléon, who had known her personally, was elected Pope with the name Urban IV, and promulgated the feast for the whole of the western Church in 1264, shortly before his own death. The bull of promulgation (which makes no mention of the miracle of the priest Peter) is known from its opening word as Transiturus, and is such a beautiful piece of writing that it was commonly read in the Divine Office in the Middle Ages. Here is its beginning.
“Transiturus de mundo ad Patrem Salvator noster Dominus Jesus Christus, cum tempus suae passionis instaret, sumpta coena, in memoriam mortis suae instítuit summum et magnificum sui Corporis et Sanguinis sacramentum: Corpus in cibum, et Sánguinem in poculum tribuendo. Nam quotiescumque hunc panem manducamus, et calicem bibimus, mortem Domini annuntiamus. In institutione quidem hujus salutiferi Sacramenti, dixit ipse Apostolis: Hoc facite in meam commemorationem: ut praecipuum et insigne memoriale sui amoris, quo nos dilexit, esset nobis hoc praecelsum et venerabile Sacramentum, memoriale, inquam, mirabile ac stupendum, delectabile ac suave, tutissimum ac sitibundum, carissimum et super omnia pretiosum. In quo innovata sunt signa, et mirabilia immutata, in quo habetur omne delectamentum, et omnis saporis suavitas, ipsaque dulcedo Domini degustatur; in quo utique vitae suffragium consequimur, et salutis. Hoc est memoriale dulcissimum, memoriale sanctissimum, memoriale salvificum, in quo gratam redemptionis nostrae recensemus memoriam, in quo a malo retrahimur, confortamur in bono, et ad virtutem et gratiarum proficimus incrementa, et in quo profecto reficimur ipsius corporali praesentia.”
When Our Savior, the Lord Jesus Christ, was about to pass from this world to the Father, as the time of His Passion drew nigh, having taken supper, He instituted unto the memory of His death the most exalted and magnificent Sacrament of His Body and Blood, giving His Body to eat and His Blood to drink. For however so often we eat this bread and drink this cup, we proclaim the death of the Lord. In the institution of this saving Sacrament, He said to the Apostles, “Do this in memory of Me”, so that this august and venerable Sacrament might be the special and particular memorial of the exceptional love with which He loved us: this memorial, I say, wondrous and astounding, full of delight, sweet, most secure, and precious above all things, in which signs are renewed and wonders changed, in which is contained every delight and the enjoyment of every savor, and the very sweetness of the Lord is tasted, by which we do indeed obtain the support of our life and salvation. This is the memorial most sweet, most sacred, most holy, profitable unto salvation, by which we recall the grace of our redemption; by which we are drawn away from evil and strengthened in good, and advance to the increase of virtues and graces, by the bodily presence of the Savior.”