The Holy Eucharist is a sacrament and a sacrifice. In the Holy Eucharist, under the appearances of bread and wine, the Lord Christ is contained, offered, and received.The whole Christ is really, truly, and substantially present in the Holy Eucharist. We use the words "really, truly, and substantially" to describe Christ's presence in the Holy Eucharist in order to distinguish Our Lord's teaching from that of mere men who falsely teach that the Holy Eucharist is only a sign or figure of Christ, or that He is present only by His power. The word "Eucharist" means "Thanksgiving."
Christ instituted the Holy Eucharist in this way: He took bread, blessed and broke it, and giving it to His apostles, said:
"Take and eat; this is My body;"then He took a cup of wine, blessed it, and giving it to them, said:
"All of you drink of this; for this is My blood of the new covenant which is being shed for many unto the forgiveness of sins;" finally, He gave His apostles the commission:
"Do this in remembrance of Me."Because the appearances of bread and wine remain in the Holy Eucharist, we cannot see Christ with our bodily eyes in this sacrament. We do see Him, however, with the eyes of faith. Our bodily eyes, moreover, do not deceive us when they see the appearances of bread and wine for these appearances really remain after the Consecration of the Mass. For the Catholic Christian, the Eucharist is our communion with the Divine Life.