"In Baptism we have been called to form but one body. The Eucharist fulfills this call: 'The cup of blessing which we bless, is it not a participation in the blood of Christ? the bread which we break, is it not a participation in the body of Christ? Because there is one bread, we who [...]
"The Eucharist is the sacrament of ecclesiastical unity, which is brought about by many being 'one in Christ.'" Source: St. Thomas Aquinas, Summa Theologica
"The Eucharist and the unity of Christians. Before the greatness of this mystery St. Augustine exclaims, 'O sacrament of devotion! O sign of unity! O bond of charity!' The more painful the experience of the divisions in the Church which break the common participation in the table of the Lord, the more urgent are our [...]
"The unity of the Mystical Body: the Eucharist makes the Church. Those who receive the Eucharist are united more closely to Christ. Through it Christ unites them to all the faithful in one body - the Church. Communion renews, strengthens, and deepens this incorporation into the Church, already achieved by Baptism." Source: Catechism of [...]
"You must make the idea of unity predominate throughout your whole life by the thought of the Eucharist. Unity comprises Our Lord entirely: His past life, which prepared the Eucharist; His present life, which is passed under your eyes and of which you behold the virtues; His future life, which will be only the extension, [...]
"With all the greater reason, then, it is not permissible for us, in thought, life or action, to take away from this truly most holy Sacrament its full magnitude and its essential meaning. It is at one and the same time a Sacrifice-Sacrament, a Communion-Sacrament, and a Presence-Sacrament And, although it is true that the [...]
"The sovereign end of Communion is to form unity of life and person between Jesus Christ and us. It is not perfect if we do not arrive at that,—for it is not our works alone that He desires when descending into us, but ourselves. It seems to me that Our Lord, on quitting the tabernacle [...]
"The Eucharist is the most perfect Sacrament of this union. By celebrating and also partaking of the Eucharist we unite ourselves with Christ on earth and in heaven who intercedes for us with the Father but we always do so through the redeeming act of his Sacrifice, through which he has redeemed us, so that [...]
"It (Eucharist) was instituted not for satisfaction, but for nourishing spiritually through union between Christ and His members, as nourishment is united with the person nourished. But because this union is the effect of charity, from the fervor of which man obtains forgiveness, not only of guilt but also of punishment, hence it is that [...]
"The personal relationship which the individual believer establishes with Jesus present in the Eucharist constantly points beyond itself to the whole communion of the Church and nourishes a fuller sense of membership in the Body of Christ." Source: Pope Benedict XVI, SACRAMENTUM CARITATIS (Sacrament of Charity), 2/22/2007