Matthew, Chapter 28, verse 8
Even before its universal promotion in 1314, Corpus Christi was one of the grandest feasts of the Roman rite. At the request of Pope Urban IV (d. 1264), the Mass proper’s and divine office for this day were composed or arranged by St. Thomas Aquinas, whose teaching on the Real Presence was so profound that the figure of Jesus Christ once descended from a crucifix and declared to him, "Thou hast written well of me, Thomas." The mastery with which Aquinas weaves together the scriptural, poetic, and theological texts of this feast amply corroborates this conclusion.
By its very nature, the Corpus Christi procession encouraged pageantry. In addition to the grandeur mentioned above, vivid symbolic reenactments of various teachings became a part of the procession. During the height of baroque piety, people impersonating demons would run along aside the Blessed Sacrament, pantomiming their fright and fear of the Real Presence. Others would dress as ancients gods and goddesses to symbolize how even the pagan past must rise and pay homage to Christ. Still others would carry all sorts of representations of sacred history: Moses and the serpent, David and Goliath, the Easter lamb, the Blessed Virgin, etc. But the most popular of all these was the custom of having children dress as angels. Appearing in white (with or without wings), these boys and girls would precede the Blessed Sacrament as symbols of the nine choirs of heavenly hosts who ever adore the Panis Angelicum, the Bread of Angels.
At Holy Trinity German Church, the Corpus Christi procession was the most important of the year. One witness to the procession of 1851 wrote:
Eternal Father, turn Your merciful gaze upon lukewarm souls who are nonetheless enfolded in the Most Compassionate Heart of Jesus. Father of Mercy, I beg You by the bitter Passion of Your Son and by His three-hour agony on the Cross: Let them, too, glorify the abyss of Your mercy. Amen.