Catechesis mystagog 4

The teaching of blessed Paul seemeth of itself enough instruction for you concerning those Divine Mysteries, whereof, if ye be made worthy, ye become therein, (so to speak,) of one Body and of one Blood with Christ. Paul saith that our Lord Jesus Christ, the same night in which he was betrayed, took bread; and when he had given thanks, he brake it, and gave it unto his disciples, saying: Take, eat; this is my Body. After the same manner also he took the cup, (saith the apostle,) and gave thanks, and said: Take this, and drink it; this is my Blood. Since therefore it is he who hath definitely stated and said, concerning that bread: This is my Body: who will dare any longer to doubt that it is so? And since it is he again that hath absolutely affirmed and said, concerning that cup: This is my Blood: who is he that will doubt any longer, or say that it is not his Blood?

In the beginning of his ministry, at Cana in Galilee, the Lord turned water into wine, a thing which hat but a few qualities in common with blood; and shall we deem him less worthy that we should believe him, when he turneth wine into Blood? He was bidden to that marriage, wherein twain were made one flesh, and he did this beginning of his miracles to the amazement of all; and shall we less surely hold that he hath given unto us his Body and Blood, to be our meat and drink? Or shall we not receive this Sacrament in full faith, that it is verily his Body and his Blood? Under the veil of bread he giveth unto us his body, and under the veil of wine, his Blood; and when thou shalt come to receive it, it is on the Body and Blood of Christ that thou wilt feed, being made a partaker of his Body and of his Blood. Thus indeed it is that we become Christ-bearers, namely, by carrying about Christ in our bodies, when we receive his body, and his Blood into our members. Thus, as blessed Peter hath it, we are partakers of the divine nature.

Christ once said, in conversing with the Jews: Except ye eat the Flesh of the Son of Man, and drink his Blood, ye have no life in you. But they took not spiritually that which he said, and from that time many of his disciples went back, and walked no more with him. They thought that he had bidden them to eat carnal flesh. This Old Testament also had shew-bread, but this Old Testament bread was now to have an end. The bread of the New Testament is the Bread which cometh down from heaven. The cup of the New Testament is the Cup of Salvation. And that Bread and that Cup do hallow both souls and bodies. Wherefore I will have thee to understand that the Bread and Wine whereunto thou art to come, are not mere common bread or mere common wine; for they are the Body and the Blood of Christ. Even if thy senses do indeed deny this fact, yet let faith make thee right sure of it. Judge not the thing by the taste thereof, but let faith assure thee beyond all doubt that thou are partaking of the Body and Blood of Christ.