Since it was the will of God’s only-begotten Son that men should share in His divinity, He assumed our nature in order that by becoming man He might make men gods. Moreover, when He took our flesh He dedicated the whole of its substance to our salvation. He offered His body to God the Father on the altar of the cross as a sacrifice for our reconciliation. He shed His blood for our ransom and purification, so that we might be redeemed from our wretched state of bondage and cleansed from all sin. But to ensure that the memory of so great a gift would abide with us for ever, He left His Body as food and His Blood as drink for the faithful to consume in the form of bread and wine.
-- Saint Thomas Aquinas
