In my belief, the physical form of the body and blood is symbolic, and spiritually complete. It does not mean that I believe the host is turned into the actual body (molecularly speaking) of Jesus Christ (which in itself may be some sort of heresy for me to state). It is accepting that Jesus Christ is eternal, and accessible spiritually, through that doorway, and that through that particular sacrament, there is a spiritual grace given. To me it stays and looks like bread and wine, but the essence of it takes on the spiritual quality of God's love through Jesus's sacrifice. It is a spiritual communion. Has very little to do with the physical substances for me, they are based on metaphor and related to traditions of the time. Anyways, I do not have a microscope to examine whether the host and wine are physically changed into the actual blood and body of Jesus Christ, for those who believe, it is a matter of faith, of transubstantiation. For me, the Eucharist, communion, it is a reminder of the sacrifice made by Jesus.

He was redefining a lot of ideas in Judaism (and those ideas would eventually evolve into Christianity), it needs to be seen from a historical, not only a faith-based perspective, to understand. To understand what was required of Him as a Jew at the time of Pesach. He did not choose to bring an offering, a sacrifice of an animal (the "body" or flesh, and the "blood") to the temple for Pesach. He was saying to his Apostles at the "last supper" while holding up the bread which he had blessed, that metaphorically He...Himself, would be the sacrifice He would give to the "altar" of the world, on Pesach. "This is My flesh..." (to give to the temple on Pesach, I am not bringing the flesh of an animal to be sacrificed this year, as is required), "This is My blood..." (it will not be a lamb's blood at the temple this year, I am sacrificing something different). Does it make any sense now? That it is not being done, or was not originally intended, to be some sort of cannibalistic or joke about vampirism, He was pointing to His death that He knew was coming, and was replacing the blood of an animal shed at the temple that year for His own? It is metaphor. That He was greater than any sacrifice He could bring, and what He was choosing to do, He was doing out of love and a will to Redeem, and as the Son of God, it was a sacrifice only He could make. He shared the bread with his friends, and the wine, to remind them of the company they were sharing that night, and what he was choosing to do in becoming the Pesach "sacrificial lamb." The bread and wine are only symbolic of that sacrifice.

When He said, "Do this in memory of me," He was asking those who celebrate the Eucharist to in a way join Him for that last meal, take part, and realize the enduring love of His sacrifice. It was built on spiritual metaphor, and done in remembrance, and a wish to be closer to Jesus and understand His sacrifice.

Of course it is a ritual, in a loose sense. There are different types of rituals found in many religions, the Abrahamic religions are full of them, as well as many other old ones, and new ones, alike.