The Feast of Corpus Christi is very accurately discussed in Wikipedia, which records that the feast has its roots among communities of women mystics in the early 1200’s, particularly Juliana of Liège, Belgium. One of the significant discoveries of modern scholarship is the widespread activity and attraction of mystics throughout medieval times, particularly in the Lowlands. The Eucharist was the center of much local piety, and there seemed to be regret that the only true feast of the Eucharist on the Church calendar was Holy Thursday, which even in today’s Missal ends on a somber note of the stripping of the altars. Corpus Christi was established on the Thursday after Trinity Sunday, originally as a holy day of obligation. In my youth the feast was celebrated on Thursday, but the solemn procession took place the following Sunday after the high Mass. The 1970 calendar allows for the feast to be celebrated as a Holy Day on Thursday or, as in the U.S., a Sunday solemnity.
As a side note, Corpus Christi has long been a day of processions. I remember walking in my parish’s procession in my white first communion suit with the class. My own diocese presently holds one in downtown Orlando. Pope Francis will process between two of Rome’s greatest churches, St. John Lateran and St. Mary Major. (St. John’s is the home of the heads of Sts. Peter and Paul, or so the claim is made. I’m on the fence about that.)
The Gospel, not surprisingly, focuses on the reality of the Eucharistic meal as the New Passover (14: 12-16) and the Real Presence of the Body and Blood of Christ (14: 22-26). At the time of the establishment of this feast medieval universities were formulating the technical language of Eucharistic understanding. The term we use today in textbooks is transubstantiation, a change from the reality of bread and wine to the living body and blood of Jesus Christ. The doctrine of Real Presence is one of the central mysteries of the Catholic faith, and probably a mystery that is long due for pastoral reeducation.
The one danger inherent in discussion of Eucharistic presence and personal piety is a lapse into physicalism, or a preoccupation with the miracle to the exclusion of its overall meaning in the life of the Church. After all, if the entire meaning of the Eucharistic sacrament is the presence of God, we would be in the same position as pre-Diaspora Jews who believed that God lived in the Holy of Holies. Jesus himself, a Jew who lived in that era, spoke little about the temple and a great deal about the heart and conduct of the true believer. He replaced a practice of objective divine presence with a highly personal one, inviting each believer to ingest himself—a teaching so difficult that most of his followers left him, as we will hear later this summer in the five weeks of John’s Gospel, chapter 6.
Thus the study of the Eucharist has shifted from the metaphysical to the Biblical and liturgical sciences in the last century. The epic work on the Scriptural Last Supper narratives is The Eucharistic Words of Jesus by Joachim Jeremias. This work was written in 1955 but was recently republished. (Amazon Prime is currently out of copies, a sign of the book’s enduring usefulness.) I wouldn’t recommend it as a cold purchase, but if you are planning advanced studies in liturgy, and you see a decent copy sitting in an offbeat bookstore for $6.95, grab it.
Biblical scholarship has truly defined a greater understanding of the Eucharist by restoring its connection to Jewish Passover. The phrase “do this in memory of me” has tremendous power in Jewish context, as the act of “remembering” is to bring into this moment the reality and effect of the thing remembered. Passover is an obvious case in point: to this day Jews celebrate the liberating deeds of God through Moses not as a 3000th anniversary, but as a restoral of the very moment. As the Synoptic Gospels clearly identify the Last Supper as a Passover, Jesus is establishing a Hebrew-like memorial where his saving crucifixion and resurrection become real in the moment whenever break is broken in his “memory.” I should say that the English language has no equivalent word or term for the Jewish sense of memorial, so our catechetics often comes up short….unless one is biblically oriented.
I have no idea if those Lowland medieval mystics understood all of this Biblical history behind the Eucharistic sacrament….but they sure had a good idea.