The Feast of Corpus Christi, or the Feast of the Body and Blood of Christ (as it is often called today), goes back to the 13th century, but it celebrates something far older: the institution of the Sacrament of Holy Communion.
While Holy Thursday is also a celebration of this mystery, the solemn nature of Holy Week, and the focus on Christ’s Passion on Good Friday, overshadows that aspect of Holy Thursday.
The feast is celebrated Thursday after Trinity Sunday, although, in the United States, the celebration is transferred to the following Sunday.
For centuries after the celebration was extended to the universal Church, the feast was celebrated with a Eucharistic procession, in which the Sacred Host was carried throughout the town, accompanied by hymns and litanies.
The faithful would venerate the Body of Christ as the procession passed by. In recent years, this practice has almost disappeared, though some parishes still hold a brief procession around the outside of the parish church. (8:30)