When, in the thirteenth century, the Waldenses and Albigenses...
spread false doctrines concerning the Blessed Sacrament, divine
Providence ordained that, in opposition to these errors, a public
profession of faith should be made by all Christendom. The will of God
was made known to an obscure and pious religious named Juliana who lived
near Liege. This humble and devout person had been privileged to behold
in her lifetime heavenly mysteries... In a vision she saw the full moon
in its splendor, one dark spot only marring the brilliance of its orb.
It was revealed to her that this spot denoted the absence of a festival
which should be devoted exclusively to honoring the Most Holy Sacrament.
At the same time it was enjoined upon her to tell this to the bishop,
and suggest that he should celebrate such a feast with the clergy of his
diocese. Another religious had a similar vision about the same time,
and also a recluse of the name of Eva. The bishop approved the idea of a
festival with this object as tending to promote the glory of God and
good of souls, and instituted it in his diocese. The new festival
commended itself to all the faithful, and in 1264 Pope Urban IV, who had
formerly been archdeacon of Liege, made it binding upon the whole
Church...
The festival is called the feast of Corpus Christi, the body of
Christ... It was for this day that St. Thomas of Aquinas composed the
beautiful hymn Lauda Sion, which is recited after the epistle. At the
conclusion of this sequence it is customary in some places to expose on
this day the Bread of Angels in the monstrance, and give the blessing
with it. After High Mass there is a solemn procession, in which the
highest ecclesiastic present carries the sacred Host beneath a canopy,
accompanied by the clergy.
An Explanation Of The Holy SacramentsRev. H. Rolfus, D.D