"Because Christ himself is present in the sacrament of the altar, he is to be honored with the worship of adoration. 'To visit the Blessed Sacrament is . . . a proof of gratitude, an expression of love, and a duty of adoration toward Christ our Lord' (Paul VI, MF 66)." Source: Catechism of [...]
"Anyone who desires to receive Christ in Eucharistic communion must be in the state of grace. Anyone aware of having sinned mortally must not receive communion without having received absolution in the sacrament of penance." Source: Catechism of the Catholic Church #1415
"As sacrifice, the Eucharist is also offered in reparation for the sins of the living and the dead and to obtain spiritual or temporal benefits from God." Source: Catechism of the Catholic Church #1414
"By the consecration the transubstantiation of the bread and wine into the Body and Blood of Christ is brought about. Under the consecrated species of bread and wine Christ himself, living and glorious, is present in a true, real, and substantial manner: his Body and his Blood, with his soul and his divinity (cf. Council [...]
"It is Christ himself, the eternal high priest of the New Covenant who, acting through the ministry of the priests, offers the Eucharistic sacrifice, and it is the same Christ, really present under the species of bread and wine, who is the offering of the Eucharistic sacrifice." Source: Catechism of the Catholic Church #1410 [...]
"The Eucharist is the memorial of Christ's Passover, that is, of the work of salvation accomplished by the life, death, and resurrection of Christ, a work made present by the liturgical action." Source: Catechism of the Catholic Church #1409
"The Eucharistic celebration always includes: the proclamation of the Word of God; thanksgiving to God the Father for all his benefits, above all the gift of his Son; the consecration of bread and wine; and participation in the liturgical banquet by receiving the Lord's body and blood. These elements constitute one single act of worship." [...]
"The Eucharist is the heart and the summit of the Church's life, for in it Christ associates his Church and all her members with his sacrifice of praise and thanksgiving offered once for all on the cross to his Father; by this sacrifice he pours out the graces of salvation on his Body which is [...]
"There is no surer pledge or dearer sign of this great hope in the new heavens and new earth 'in which righteousness dwells,' than the Eucharist. Every time this mystery is celebrated, 'the work of our redemption is carried on' and we 'break the one bread that provides the medicine of immortality, the antidote for [...]
"The Church knows that the Lord comes even now in his Eucharist and that he is there in our midst. However, his presence is veiled. Therefore we celebrate the Eucharist 'awaiting the blessed hope and the coming of our Savior, Jesus Christ,' asking 'to share in your glory when every tear will be wiped away. [...]