"`I have received of the Lord that which I also delivered unto you, that the Lord Jesus, the same night in which He was betrayed, took bread, etc. [1 Cor. 11:23]'. This teaching of the Blessed Paul is alone sufficient to give you a full assurance concerning those Divine Mysteries, which when ye are vouchsafed, ye are of (the same body) [Eph 3:6] and blood with Christ. For he has just distinctly said, (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 said, Take, eat, this is My Body: and having taken the cup and given thanks, He said, Take, drink, this is My Blood.) [1 Cor. 2:23-25] Since then He Himself has declared and said of the Bread, (This is My Body), who shall dare to doubt any longer? And since He has affirmed and said, (This is My Blood), who shall ever hesitate, saying, that it is not His blood?
-"Catechetical Lectures [22 (Mystagogic 4), 1]
"Therefore with fullest assurance let us partake as of the Body and Blood of Christ: for in the figure of Bread is given to thee His Body, and in the figure of Wine His Blood; that thou by partaking of the Body and Blood of Christ, mightest be made of the same body and the same blood with Him. For thus we come to bear Christ in us, because His Body and Blood are diffused through our members; thus it is that, according to the blessed Peter, (we become partaker of the divine nature.) [2 Peter 1:4]
-"Catechetical Lectures [22 (Mystagogic 4), 3]
"Contemplate therefore the Bread and Wine not as bare elements, for they are, according to the Lord's declaration, the Body and Blood of Christ; for though sense suggests this to thee, let faith stablish thee. Judge not the matter from taste, but from faith be fully assured without misgiving, that thou hast been vouchsafed the Body and Blood of Christ.
-"Catechetical Lectures [22 (Mystagogic 4), 6]"
"9. These things having learnt, and being fully persuaded that what seems bread is not bread, though bread by taste, but the Body of Christ; and that what seems wine is not wine, though the taste will have it so, but the Blood of Christ; and that of this David sung of old, saying, (And bread which strengtheneth man's heart, and oil to make his face to shine) [Ps. 104:15],
strengthen thine heart', partaking thereof as spiritual, andmake the face of thy soul to shine'. And so having it unveiled by a pure conscience, mayest thou behold as in a glass the glory of the Lord, and proceed from glory to glory [2 Cor. 3:18], in Christ Jesus our Lord:--To whom be honor, and might, and glory, for ever and ever. Amen."
Source: St. Cyril of Jerusalem, Mystagogic Catechesis 4,1, c. 350 A.D.:
"Then upon the completion of the spiritual Sacrifice, the bloodless worship, over the propitiatory victim we call upon God for the common peace of the Churches, for the welfare of the world, for kings, for soldiers and allies, for the sick, for the afflicted; and in summary, we all pray and offer this Sacrifice for all who are in need."
"Mystagogic Catechesis [23: 5-7]
"Then we make mention also of those who have already fallen asleep: first, the patriarchs, prophets, Apostles, and martyrs, that through their prayers and supplications God would receive our petition; next, we make mention also of the holy fathers and bishops who have already fallen asleep, and, to put it simply, of all among us who have already fallen asleep; for we believe that it will be of very great benefit of the souls of those for whom the petition is carried up, while this holy and most solemn Sacrifice is laid out."
-Mystagogic Catechesis [23 (Mystagogic 5), 10]
"After this you hear the singing which invites you with a divine melody to the Communion of the Holy Mysteries, and which says, 'Taste and see that the Lord is good.' Do not trust to the judgement of the bodily palate - no, but to unwavering faith. For they who are urged to taste do not taste of bread and wine, but to the antitype, of the Body and Blood of Christ."
-"Mystagogic Catecheses 5 23, 20 ca. 350 A.D
"Keep these traditions inviolate, and preserve yourselves from offenses. Do not cut yourselves off from Communion, do not deprive yourselves, through the pollution of sins, of these Holy and Spiritual Mysteries."
-"Mystagogic Catechesis [23 (Mystagogic 5), 23]"