The Communion of Saints
“The term “communion of saints” therefore has two closely linked meanings: communion “in holy things (sancta)” and “among holy persons (sancti).”"
After confessing “the holy catholic Church,” the Apostles’ Creed adds “the communion of saints.” In a certain sense this is a further explanation of the preceding: “What is the Church if not the assembly of all the saints?”The communion of saints is the Church.
“Since all the faithful form one body, the good of each is communicated to the others. . . . We must therefore believe that there exists a communion of goods in the Church. But the most important member is Christ, since he is the head. . . . Therefore, the riches of Christ are communicated to all the members, through the sacraments. As this Church is governed by one and the same Spirit, all the goods she has received necessarily become a common fund.”
The term “communion of saints” therefore has two closely linked meanings: communion “in holy things (sancta)” and “among holy persons (sancti).”
Sancta sanctis! (“God’s holy gifts for God’s holy people”) is proclaimed by the celebrant in most Eastern liturgies during the elevation of the holy Gifts before the distribution of communion. The faithful (sancti) are fed by Christ’s holy body and blood (sancta) to grow in the communion of the Holy Spirit (koinonia) and to communicate it to the world. (CCC 946-948)
In the Holy Sacrifice of the Mass
You will notice that, during the Holy Sacrifice of the Mass, while the choir chants the Agnus Dei, the priest will break the Host into three pieces. Two parts are left upon the paten, while one part (which is very small) is placed into the chalice of the Precious Blood. This is called the rite of “commingling”, because it is at this point that the Body and Blood of Christ are sacramentally mingled together – though the Lord is fully present in both the Host and the chalice, the one is the Sacrament of his Body and the other is the Sacrament of his Blood. As the priest performs this rite he prays: “May this mingling of the Body and Blood of our Lord Jesus Christ bring eternal life to us who receive it.” There is, in the very rite itself, a direct connection between the commingling and salvation! St. Thomas Aquinas, following an ancient tradition, has shown how the whole Church is mystically present in this sacramental rite.