And this food is called among us Eukaristia [the Eucharist], of which no one is allowed to partake but the man who believes that the things which we teach are true, and who has been washed with the washing that is for the remission of sins, and unto regeneration, and who is so living as Christ has commanded. For not as common bread and common drink do we receive these; but in like manner as Jesus Christ our Savior, having been made flesh by the Word of God, had both flesh and blood for our salvation, so likewise have we been taught that the food which is blessed by the prayer of His word, and from which our blood and flesh by transmutation are nourished, is the flesh and blood of that Jesus who was made flesh. For the apostles, in the memoirs composed by them, which are called Gospels, have thus delivered unto us what was commanded upon them; that Jesus took bread, and when He had given thanks, said, “This do you in remembrance of Me, this is My body;” and that, after the same manner, having taken the cup and given thanks, He said, “This is My blood;” and gave it to them alone.
But we, after we have thus washed him who has been convinced and has assented to our teaching, bring him to the place where those who are called brethren are assembled, having ended the prayers, we salute one another with a kiss. There is then brought to the president of the brethren bread and a cup of wine mixed with water; and he taking them, gives praise and glory to the Father of the universe, through the name of the Son and of the Holy Ghost…And when the president has given thanks, and all the people have expressed their assent, those who are called by us deacons give to each of those present to partake of the bread and wine mixed with water over which the thanksgiving was pronounced, and to those who are absent they carry away a portion. – ibid
“And the offering of fine flour, sirs,” I said, “which was prescribed to be presented on behalf of those purified from leprosy, was a type of the bread of the Eucharist, the celebration of which our Lord Jesus Christ prescribed, in remembrance of the suffering which He endured on behalf of those who are purified in soul from all iniquity, in order that we may at the same time thank God for having created the world, -ibid
Accordingly, God, anticipating all the sacrifices which we offer through this name, and which Jesus the Christ commanded us to offer, i.e., in the Eucharist of the bread and the cup, and which are presented by Christians in all places throughout the world, bears witness that they are well-pleasing to Him. -ibid
Again, giving directions to His disciples to offer to God the first-fruits of His own, created things-not as if He stood in need of them, but that they might be themselves neither unfruitful nor ungrateful-He took that created thing, bread, and gave thanks, and said, “This is My body.” And the cup likewise, which is part of that creation to which we belong, He confessed to be His blood, and taught the new oblation of the new covenant; which the Church receiving from the apostles, offers to God throughout all the world.
As far as concerned the apostasy, indeed, He redeems us righteously from it by His own blood… By His own blood he redeemed us, as also His apostle declares, “In whom we have redemption through His blood, even the remission of sins.” And as we are His members, we are also nourished by means of the creation (and He Himself grants the creation to us, for He causes His sun to rise, and sends rain when He wills). He has acknowledged the cup (which is a part of the creation) as His own blood, from which He bedews our blood; and the bread (also a part of the creation) He has established as His own body, from which He gives increase to our bodies. -ibid
The Word of God becomes the Eucharist, which is the body and blood of Christ; so also our bodies, being nourished by it, and deposited in the earth, and suffering decomposition there, shall rise at their appointed time, the Word of God granting them resurrection to the glory of God, even the Father, who freely gives to this mortal immortality, and to this corruptible incorruption, because the strength of God is made perfect in weakness, in order that we may never become puffed up, as if we had life from ourselves, and exalted against God, our minds becoming ungrateful. -ibid
Clement of Alexandria
And the blood of the Lord is twofold. For there is the blood of His flesh, by which we are redeemed from corruption; and the spiritual, that by which we are anointed. And to drink the blood of Jesus, is to become partaker of the Lord’s immortality; the Spirit being the energetic principle of the Word, as blood is of flesh…And the mixture of both – of the water and of the Word – is called Eucharist, renowned and glorious grace; and they who by faith partake of it are sanctified both in body and soul. For the divine mixture, man, the Father’s will has mystically compounded by the Spirit and the Word.
Now concerning the Eucharist, give thanks this way…
First, concerning the cup: We thank you, our Father, for the holy vine of David Your servant, which You made known to us through Jesus Your Servant; to You be the glory for ever..
And concerning the broken bread: We thank You, our Father, for the life and knowledge which You made known to us through Jesus Your Servant; to You be the glory for ever. Even as this broken bread was scattered over the hills, and was gathered together and became one, so let Your Church be gathered together from the ends of the earth into Your kingdom; for Yours is the glory and the power through Jesus Christ for ever..
But let no one eat or drink of your Eucharist, unless they have been baptized into the name of the Lord; for concerning this also the Lord has said, “Give not that which is holy to the dogs.”
But after you are filled, give thanks this way:
We thank You, holy Father, for Your holy name which You didst cause to tabernacle in our hearts, and for the knowledge and faith and immortality, which You madest known to us through Jesus Your Servant; to You be the glory for ever. You, Master almighty, didst create all things for Your name’s sake; You gave food and drink to men for enjoyment, that they might give thanks to You; but to us You didst freely give spiritual food and drink and life eternal through Your Servant. Before all things we thank You that You are mighty; to You be the glory for ever. Remember, Lord, Your Church, to deliver it from all evil and to make it perfect in Your love, and gather it from the four winds, sanctified for Your kingdom which You have prepared for it; for Yours is the power and the glory for ever. Let grace come, and let this world pass away. Hosanna to the God (Son) of David! If any one is holy, let him come; if any one is not so, let him repent. Maranatha. Amen.
Since, then, neither the apostle himself nor an angel from heaven can preach or teach any otherwise than Christ has once taught and His apostles have announced, I wonder very much whence has originated this practice, that, contrary to evangelical and apostolic discipline, water is offered in some places in the Lord’s cup, which water by itself cannot express the blood of Christ. The Holy Spirit also is not silent in the Psalms on the sacrament of this thing, when He makes mention of the Lord’s cup, and says, “Your inebriating cup, how excellent it is!” Now the cup which inebriates is assuredly mingled with wine, for water cannot inebriate anybody. And the cup of the Lord in such wise inebriates, as Noah also was intoxicated drinking wine, in Genesis. But because the intoxication of the Lord’s cup and blood is not such as is the intoxication of the world’s wine, since the Holy Spirit said in the Psalm, “Your inebriating cup,” He added, “how excellent it is,” because doubtless the Lord’s cup so inebriates them that drink, that it makes them sober; that it restores their minds to spiritual wisdom; that each one recovers from that flavor of the world to the understanding of God; and in the same way, that by that common wine the mind is dissolved, and the soul relaxed, and all sadness is laid aside, so, when the blood of the Lord and the cup of salvation have been drunk, the memory of the old man is laid aside, and there arises an oblivion of the former worldly conversation, and the sorrowful and sad breast which before was oppressed by tormenting sins is eased by the joy of the divine mercy; because that only is able to rejoice him who drinks in the Church which, when it is drunk, retains the Lord’s truth.