From the Catechism of the Catholic Church we read the development of this truth from scriptures as it has been practiced since the beginnings of Christianity:

1373 "Christ Jesus, who died, yes, who was raised from the dead, who is at the right hand of God, who indeed intercedes for us," is present in many ways to his Church:197 in his word, in his Church's prayer, "where two or three are gathered in my name,"198 in the poor, the sick, and the imprisoned,199 in the sacraments of which he is the author, in the sacrifice of the Mass, and in the person of the minister. But "he is present . . . most especially in the Eucharistic species."

*197 Rom 8:34 
*198 Mt 18:20 
*199 Mt 25:31-46

1374 The mode of Christ's presence under the Eucharistic species is unique. It raises the Eucharist above all the sacraments as "the perfection of the spiritual life and the end to which all the sacraments tend." In the most blessed sacrament of the Eucharist "the body and blood, together with the soul and divinity, of our Lord Jesus Christ and, therefore, the whole Christ is truly, really, and substantially contained." "This presence is called 'real' - by which is not intended to exclude the other types of presence as if they could not be 'real' too, but because it is presence in the fullest sense: that is to say, it is a substantial presence by which Christ, God and man, makes himself wholly and entirely present."

1329 The Lord's Supper, because of its connection with the supper which the Lord took with his disciples on the eve of his Passion and because it anticipates the wedding feast of the Lamb in the heavenly Jerusalem.143
The Breaking of Bread, because Jesus used this rite, part of a Jewish meal, when as master of the table he blessed and distributed the bread,144 above all at the Last Supper.145 It is by this action that his disciples will recognize him after his Resurrection,146 and it is this expression that the first Christians will use to designate their Eucharistic assemblies;147 by doing so they signified that all who eat the one broken bread, Christ, enter into communion with him and form but one body in him.148

*143 1 Cor 11:20; Rev 19:9
*144 Mt 14:19; 15:36; Mk 8:6, 19
*145 Mt 26:26
26 Now as they were eating, Jesus took bread, and when he had said the blessing he broke it and gave it to the disciples. 'Take it and eat,' he said, 'this is my body.'

*145 1 Cor 11: 23-26
23 For the tradition I received from the Lord and also handed on to you is that on the night he was betrayed, the Lord Jesus took some bread,
24 and after he had given thanks, he broke it, and he said, 'This is my body, which is for you; do this in remembrance of me.'
25 And in the same way, with the cup after supper, saying, 'This cup is the new covenant in my blood. Whenever you drink it, do this as a memorial of me.'
26 Whenever you eat this bread, then, and drink this cup, you are proclaiming the Lord's death until he comes.

*146 Lk 24:13-35

*147 Acts 2:42, 46
42 These remained faithful to the teaching of the apostles, to the brotherhood, to the breaking of bread and to the prayers.
46 Each day, with one heart, they regularly went to the Temple but met in their houses for the breaking of bread…

*147 Act 20.7-12
7 On the first day of the week we met for the breaking of bread. Paul was due to leave the next day, and he preached a sermon that went on till the middle of the night.
8 A number of lamps were lit in the upstairs room where we were assembled,
9 and as Paul went on and on, a young man called Eutychus who was sitting on the window-sill grew drowsy and was overcome by sleep and fell to the ground three floors below. He was picked up dead.
10 Paul went down and stooped to clasp the boy to him, saying, 'There is no need to worry, there is still life in him.'
11 Then he went back upstairs where he broke the bread and ate and carried on talking till he left at daybreak.
12 They took the boy away alive, and were greatly encouraged.

*148 1 Cor 10:16, 17
16 The blessing-cup, which we bless, is it not a sharing in the blood of Christ; and the loaf of bread which we break, is it not a sharing in the body of Christ?
17 And as there is one loaf, so we, although there are many of us, are one single body, for we all share in the one loaf.

1375 It is by the conversion of the bread and wine into Christ's body and blood that Christ becomes present in this sacrament. The Church Fathers strongly affirmed the faith of the Church in the efficacy of the Word of Christ and of the action of the Holy Spirit to bring about this conversion. Thus St. John Chrysostom declares:

It is not man that causes the things offered to become the Body and Blood of Christ, but he who was crucified for us, Christ himself. The priest, in the role of Christ, pronounces these words, but their power and grace are God's. This is my body, he says. This word transforms the things offered.

And St. Ambrose says about this conversion:

Be convinced that this is not what nature has formed, but what the blessing has consecrated. The power of the blessing prevails over that of nature, because by the blessing nature itself is changed. . . . Could not Christ's word, which can make from nothing what did not exist, change existing things into what they were not before? It is no less a feat to give things their original nature than to change their nature.

1376 The Council of Trent summarizes the Catholic faith by declaring: "Because Christ our Redeemer said that it was truly his body that he was offering under the species of bread, it has always been the conviction of the Church of God, and this holy Council now declares again, that by the consecration of the bread and wine there takes place a change of the whole substance of the bread into the substance of the body of Christ our Lord and of the whole substance of the wine into the substance of his blood. This change the holy Catholic Church has fittingly and properly called transubstantiation."206

*206 Mt 26:26; Mk 14:22; Lk 22:19; 1 Cor 11:24 

1356 If from the beginning Christians have celebrated the Eucharist and in a form whose substance has not changed despite the great diversity of times and liturgies, it is because we know ourselves to be bound by the command the Lord gave on the eve of his Passion: "Do this in remembrance of me."183

*183 1 Cor 11:24-25

1357 We carry out this command of the Lord by celebrating the memorial of his sacrifice. In so doing, we offer to the Father what he has himself given us: the gifts of his creation, bread and wine which, by the power of the Holy Spirit and by the words of Christ, have become the body and blood of Christ. Christ is thus really and mysteriously made present.

1358 We must therefore consider the Eucharist as:
- thanksgiving and praise to the Father; 
- the sacrificial memorial of Christ and his Body; 
- the presence of Christ by the power of his word and of his Spirit.

1360 The Eucharist is a sacrifice of thanksgiving to the Father, a blessing by which the Church expresses her gratitude to God for all his benefits, for all that he has accomplished through creation, redemption, and sanctification. Eucharist means first of all "thanksgiving."

1361 The Eucharist is also the sacrifice of praise by which the Church sings the glory of God in the name of all creation. This sacrifice of praise is possible only through Christ: he unites the faithful to his person, to his praise, and to his intercession, so that the sacrifice of praise to the Father is offered through Christ and with him, to be accepted in him.

*The sacrificial memorial of Christ and of his Body, the Church*

1362 The Eucharist is the memorial of Christ's Passover, the making present and the sacramental offering of his unique sacrifice, in the liturgy of the Church which is his Body. In all the Eucharistic Prayers we find after the words of institution a prayer called the anamnesis or memorial.

1363 In the sense of Sacred Scripture the memorial is not merely the recollection of past events but the proclamation of the mighty works wrought by God for men.184 In the liturgical celebration of these events, they become in a certain way present and real. This is how Israel understands its liberation from Egypt: every time Passover is celebrated, the Exodus events are made present to the memory of believers so that they may conform their lives to them.

*184 Cf. Ex 13:3

1364 In the New Testament, the memorial takes on new meaning. When the Church celebrates the Eucharist, she commemorates Christ's Passover, and it is made present the sacrifice Christ offered once for all on the cross remains ever present.185 "As often as the sacrifice of the Cross by which 'Christ our Pasch has been sacrificed' is celebrated on the altar, the work of our redemption is carried out."186

*185 Heb 7:25-27
*186 1 Cor 5:7

1365 Because it is the memorial of Christ's Passover, the Eucharist is also a sacrifice. The sacrificial character of the Eucharist is manifested in the very words of institution: "This is my body which is given for you" and "This cup which is poured out for you is the New Covenant in my blood."187 In the Eucharist Christ gives us the very body which he gave up for us on the cross, the very blood which he "poured out for many for the forgiveness of sins."188

*187 Lk 22:19-20
*188 Mt 26:28

1366 The Eucharist is thus a sacrifice because it re-presents (makes present) the sacrifice of the cross, because it is its memorial and because it applies its fruit:

[Christ], our Lord and God, was once and for all to offer himself to God the Father by his death on the altar of the cross, to accomplish there an everlasting redemption. But because his priesthood was not to end with his death, at the Last Supper "on the night when he was betrayed," [he wanted] to leave to his beloved spouse the Church a visible sacrifice (as the nature of man demands) by which the bloody sacrifice which he was to accomplish once for all on the cross would be re-presented, its memory perpetuated until the end of the world, and its salutary power be applied to the forgiveness of the sins we daily commit.189

*189 1 Cor 11:23; Heb 7:24, 27

1367 The sacrifice of Christ and the sacrifice of the Eucharist are one single sacrifice: "The victim is one and the same: the same now offers through the ministry of priests, who then offered himself on the cross; only the manner of offering is different." "And since in this divine sacrifice which is celebrated in the Mass, the same Christ who offered himself once in a bloody manner on the altar of the cross is contained and is offered in an unbloody manner. . . this sacrifice is truly propitiatory."190

*190 Heb 9:14,27

1378 Worship of the Eucharist. In the liturgy of the Mass we express our faith in the real presence of Christ under the species of bread and wine by, among other ways, genuflecting or bowing deeply as a sign of adoration of the Lord. "The Catholic Church has always offered and still offers to the sacrament of the Eucharist the cult of adoration, not only during Mass, but also outside of it, reserving the consecrated hosts with the utmost care, exposing them to the solemn veneration of the faithful, and carrying them in procession."208

*208 Paul VI

1379 The tabernacle was first intended for the reservation of the Eucharist in a worthy place so that it could be brought to the sick and those absent outside of Mass. As faith in the real presence of Christ in his Eucharist deepened, the Church became conscious of the meaning of silent adoration of the Lord present under the Eucharistic species. It is for this reason that the tabernacle should be located in an especially worthy place in the church and should be constructed in such a way that it emphasizes and manifests the truth of the real presence of Christ in the Blessed Sacrament.

1380 It is highly fitting that Christ should have wanted to remain present to his Church in this unique way. Since Christ was about to take his departure from his own in his visible form, he wanted to give us his sacramental presence; since he was about to offer himself on the cross to save us, he wanted us to have the memorial of the love with which he loved us "to the end,"209 even to the giving of his life. In his Eucharistic presence he remains mysteriously in our midst as the one who loved us and gave himself up for us,210 and he remains under signs that express and communicate this love:

The Church and the world have a great need for Eucharistic worship. Jesus awaits us in this sacrament of love. Let us not refuse the time to go to meet him in adoration, in contemplation full of faith, and open to making amends for the serious offenses and crimes of the world. Let our adoration never cease.211

*209 Jn 13:1
*210 Gal 2:20
*211 John Paul II

On a sobering note. God, because believers were screwing around and not taking seriously such a preeminent doctrine, made an example of some of them. 

1 Corinthian 11: 20-34.

20 So, when you meet together, it is not the Lord's Supper that you eat;
21 for when the eating begins, each one of you has his own supper first, and there is one going hungry while another is getting drunk.
22 Surely you have homes for doing your eating and drinking in? Or have you such disregard for God's assembly that you can put to shame those who have nothing? What am I to say to you? Congratulate you? On this I cannot congratulate you.
23 For the tradition I received from the Lord and also handed on to you is that on the night he was betrayed, the Lord Jesus took some bread,
24 and after he had given thanks, he broke it, and he said, 'This is my body, which is for you; do this in remembrance of me.'
25 And in the same way, with the cup after supper, saying, 'This cup is the new covenant in my blood. Whenever you drink it, do this as a memorial of me.'
26 Whenever you eat this bread, then, and drink this cup, you are proclaiming the Lord's death until he comes.
27 Therefore anyone who eats the bread or drinks the cup of the Lord unworthily is answerable for the body and blood of the Lord.
28 Everyone is to examine himself and only then eat of the bread or drink from the cup;
29 because a person who eats and drinks without recognising the body is eating and drinking his own condemnation.
30 That is why many of you are weak and ill and a good number have died.
31 If we were critical of ourselves we would not be condemned,
32 but when we are judged by the Lord, we are corrected by the Lord to save us from being condemned along with the world.
33 So then, my brothers, when you meet for the Meal, wait for each other;
34 anyone who is hungry should eat at home. Then your meeting will not bring your condemnation. The other matters I shall arrange when I come.

A teaching moment to say the least but God was laying the foundation for the Church at it’s infancy and the truth had to be settled in order for things to move forward in His plan to save and restore humanity back to the Kingdom of His Divine Will.


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