1 Corinthians 10:16
The cup of blessing that we bless, is it not a participation in the blood of Christ? The bread that we break, is it not a participation in the body of Christ?
1 Corinthians 11:24
and, after he had given thanks, broke it and said, "This is my body that is for you. Do this in remembrance of me."
The Eucharist must be worthily received.
1 Corinthians 10:21
You cannot drink the cup of the Lord and also the cup of demons. You cannot partake of the table of the Lord and of the table of demons.
1 Corinthians 11:23-29
For I received from the Lord what I also handed on to you, that the Lord Jesus, on the night he was handed over, took bread, and, after he had given thanks, broke it and said, "This is my body that is for you. Do this in remembrance of me." In the same way also the cup, after supper, saying, "This cup is the new covenant in my blood. Do this, as often as you drink it, in remembrance of me." For as often as you eat this bread and drink the cup, you proclaim the death of the Lord until he comes. Therefore whoever eats the bread or drinks the cup of the Lord unworthily will have to answer for the body and blood of the Lord. A person should examine himself, and so eat the bread and drink the cup. For anyone who eats and drinks without discerning the body, eats and drinks judgment on himself.
The Holy Sacrifice of the Mass.
Melchizedek, king of Salem, brought out bread and wine, and being a priest of God Most High, he blessed Abram with these words:
What was required Foretold
For from the rising of the sun, even to its setting, my name is great among the nations; And everywhere they bring sacrifice to my name, and a pure offering; For great is my name among the nations, says the LORD of hosts.
Then he took the bread, said the blessing, broke it, and gave it to them, saying, "This is my body, which will be given for you; do this in memory of me."
1 Corinthians 11:25
In the same way also the cup, after supper, saying, "This cup is the new covenant in my blood. Do this, as often as you drink it, in remembrance of me."
They devoted themselves to the teaching of the apostles and to the communal life, to the breaking of the bread and to the prayers. Awe came upon everyone, and many wonders and signs were done through the apostles. All who believed were together and had all things in common; they would sell their property and possessions and divide them among all according to each one's need. Every day they devoted themselves to meeting together in the temple area and to breaking bread in their homes. They ate their meals with exultation and sincerity of heart, praising God and enjoying favor with all the people. And every day the Lord added to their number those who were being saved.
We have an altar from which those who serve the tabernacle have no right to eat.
Catechism for Mobile Devices (SCBorromeo.org)
The Catechism of the Catholic Church (USCCB.org)
Section Two: the Seven Sacraments of the Church
Chapter One: The Sacraments of Christian Initiation
Article 3: The Sacrament of the Eucharist
The Eucharist—Source and Summit of Ecclesial Life
What Is This Sacrament Called?
The Eucharist in the Economy of Salvation
The Liturgical Celebration of the Eucharist
The Sacramental Sacrifice: Thanksgiving, Memorial, Presence
The Paschal Banquet
The Eucharist—"Pledge of the Glory to Come"
The Code of Canon Law (Vatican.va)
PART I. THE SACRAMENTS
TITLE III. THE MOST HOLY EUCHARIST (Cann. 897 - 958)
CHAPTER I. THE EUCHARISTIC CELEBRATION
Art. 1. THE MINISTER OF THE MOST HOLY EUCHARIST
Art. 2. PARTICIPATION IN THE MOST HOLY EUCHARIST
Art. 3. THE RITES AND CEREMONIES OF THE EUCHARISTIC CELEBRATION
Art. 4. THE TIME AND PLACE OF THE CELEBRATION OF THE EUCHARIST
CHAPTER II. THE RESERVATION AND VENERATION OF THE MOST HOLY EUCHARIST
CHAPTER III. THE OFFERING GIVEN FOR THE CELEBRATION OF MASS
The Catholic Encyclopedia (NewAdvent.org)
Anointing of the Sick
Faith and Works
The Two Great Commandments
The Ten Commandments