Chapter Four (numbered sections 34-46), “The Eucharist and Ecclesial Communion” begins with a reference to the 1985 Synod. The suggestion here is that the Eucharist is a means to an end, namely, union with God.
34. The Extraordinary Assembly of the Synod of Bishops in 1985 saw in the concept of an “ecclesiology of communion” the central and fundamental idea of the documents of the Second Vatican Council. (Cf. Final Report, II.C.1: L’Osservatore Romano, 10 December 1985, 7.) The Church is called during her earthly pilgrimage to maintain and promote communion with the Triune God and communion among the faithful. For this purpose she possesses the word and the sacraments, particularly the Eucharist, by which she “constantly lives and grows” (Lumen Gentium, 26.) and in which she expresses her very nature. It is not by chance that the term communion has become one of the names given to this sublime sacrament.
The Eucharist thus appears as the culmination of all the sacraments in perfecting our communion with God the Father by identification with his only-begotten Son through the working of the Holy Spirit. With discerning faith a distinguished writer of the Byzantine tradition voiced this truth: in the Eucharist “unlike any other sacrament, the mystery [of communion] is so perfect that it brings us to the heights of every good thing: here is the ultimate goal of every human desire, because here we attain God and God joins himself to us in the most perfect union”. (Nicolas Cabasilas, Life in Christ, IV, 10: SCh 355, 270.)
This restates the second purpose of the liturgy as given in Sacrosanctum Concilium, the sanctification of the faithful.
Teresa of Avila is cited for the notion of a “spiritual communion.”
Precisely for this reason it is good to cultivate in our hearts a constant desire for the sacrament of the Eucharist. This was the origin of the practice of “spiritual communion”, which has happily been established in the Church for centuries and recommended by saints who were masters of the spiritual life. Saint Teresa of Jesus wrote: “When you do not receive communion and you do not attend Mass, you can make a spiritual communion, which is a most beneficial practice; by it the love of God will be greatly impressed on you”. (Camino de Perfección, Chapter 35.)