Today we celebrate not only the gift of the Eucharist, the Body, and Blood of Our Lord, but the covenant sealed through Our Lord's Precious Blood.
In today's First Reading the old covenant that the Lord established with the people of Israel is sealed with the blood of a sacrifice.
The old covenant involved the shedding and sprinkling of blood. The altar represented God, and by sprinkling the blood on it and the people a communion of life was established that would be maintained for as long as they followed the precepts stipulated.
The Lord didn't need to do it, but, after the sins of humanity, the people of Israel did. That covenant was repeatedly renewed in Jewish worship through the sacrifice of animals and the shedding of their blood, with the hope of atoning for having transgressed the covenant.
This covenant and the sacrificed blood that sealed were just a foreshadowing of the covenant to come.
When God became man, he chose to become that sacrifice, to shed his blood to establish a new and everlasting covenant. If the blood of animals produced a spiritual benefit for those who were offering it, today's Second Reading reminds us how much more spiritual benefit comes from the blood of Christ, who sacrificed himself for the sins of the world.
Moses in the First Reading ratified the covenant with the blood of bulls; the Second Reading reminds us that Jesus has ratified the new covenant with his blood. It's one thing to sacrifice something of value and make amends; it's a whole other level to sacrifice your very self, body, and blood.
In ancient religions sacrifices were made and then partaken of, eating the food or animal sacrificed, to express communion with the deity to which the sacrifice was being made.
In today's Gospel, we see Our Lord in the Last Supper establishing a new and eternal covenant that would be sealed with his sacrifice on the Cross.
Our Lord established the sacrament of his Eucharist in an unbloody way, at the Last Supper, enabling his disciples to partake of his body and blood sacramentally so that they wouldn't have to physically.
However, that didn't preclude Our Lord from physically sacrificing himself on the Cross. We celebrate today the Body and Blood of Christ because they are now the one sacrifice to restore and maintain our communion with God.
We offer and receive this sacrifice in an unbloody manner, under the appearance of bread and wine, in part because Our Lord didn't want our squeamishness to keep us from coming to him as the Bread of Life.
We remember today that the Eucharist is the Body and Blood of Christ so that we never forget that a sacrifice has been made once and for all the forgiveness of sins: our sins, not his.