I suspect the early Christians would have found the idea of a feast specifically devoted to the Body and Blood of Christ a little strange. For them the idea of participation in the Body and Blood of the Lord was built into their routine. It was a part of their life, extraordinary and completely routine. Saint Justin Martyr in the second century explained to the bemused Romans around him what the Christians did every week – no they didn’t have orgies, they didn’t sacrifice babies or drink their blood, but they did gather to listen to scripture, to a homily, and to share again in the last meal of Jesus, the meal in which he shared his body and blood as bread and wine, before sharing his body and blood hung on a gibbet.
As this “normal” event became more distinct from the daily lives of Christians, and the ceremonies became grander, and the churches became bigger, and people started to observe the rituals from a distance – so it became necessary to call out the significance of the body and blood of Jesus. And so the feast of Corpus Christi came down to us as the celebration of the Eucharist, the extraordinary and the mundane, the recognition that our God is literally and physically one with us, as our food ingested and digested becomes the very cells of our body.
Christianity is perhaps the religion most closely tied to the physical reality of our lives. For all of its theology and philosophy and mysticism and music and art, at its center it is about bodies and blood and sweat and tears, and joy and laughter. It is not a religion of ideas, it is a religion of flesh, to be felt and experienced, not analyzed and explained. It starts with a body, an in-carnated God, a God who is a person with a body just like ours. It proceeds though bread and wine and meals shared. It is demonstrated by the love that its followers display, who think of themselves as so closely associated that they are like the organs of a single body, so close that no part makes any sense or has any value independent of the others.
So the body of Christ is the beginning, and the center, and the summation of everything that makes us Christians. And so it was from the beginning and will be until the end of time.