This wonderful article in Catholic World Report by Cardinal Sarah reminds us of the ancient reason for priest and laity facing East during Mass.

An excerpt.

Fifty years after its promulgation by Pope Paul VI, will the Second Vatican Council’s Constitution on the Sacred Liturgy finally be read? Sacrosanctum Concilium is actually not just a catalogue of “recipes” for reform, but a veritable Magna Carta of all liturgical action.

In it the Ecumenical Council gives us a magisterial lesson in methodology. Indeed, far from being content with a disciplinary, external approach to the liturgy, the Council wishes to have us contemplate what it is in its essence. The Church’s practice always results from what she receives and contemplates in revelation. Pastoral ministry cannot be detached from doctrine.

In the Church “action is directed to contemplation” (cf. no. 2). The conciliar Constitution invites us to rediscover the Trinitarian origin of the liturgical work. Indeed, the Council determines that there is a continuity between the mission of Christ the Redeemer and the liturgical mission of the Church. “Just as Christ was sent by the Father, so also He sent the apostles,” so that “by means of sacrifice and sacraments, around which the entire liturgical life revolves” they might “accomplish the work of salvation” (no. 6).

Carrying out the liturgy therefore is the same as accomplishing the work of Christ. The liturgy is essentially “actio Christi”: “the work of Christ the Lord in redeeming mankind and giving perfect glory to God” (no. 5). He is the great high priest, the true subject, the true protagonist of the liturgy (cf. no. 7). If this vitally important principle is not accepted in faith, we run the risk of making the liturgy a human work, the community’s celebration of itself.

On the contrary, the Church’s real work is to enter into Christ’s action, to join in the work for which He has been commissioned by the Father. Therefore “the fullness of divine worship was given to us,” because “His humanity, united with the person of the Word, was the instrument of our salvation” (no. 5). The Church, the Body of Christ, must therefore become in turn an instrument in the hands of the Word.

This is the ultimate meaning of the key concept of the conciliar Constitution: “participatio actuosa”. For the Church, this participation consists of becoming the instrument of Christ the Priest, for the purpose of participating in His Trinitarian mission. The Church actively participates in Christ’s liturgical work insofar as she is the instrument thereof. In this sense, language about the “celebrating community” has its ambiguities and requires true caution (cf. the Instruction Redemptoris sacramentum, no. 42). Therefore this “participatio actuosa” should not be understood as the need to do something. On this point the Council’s teaching has often been distorted. Instead it is a matter of letting Christ take us and associate us with His sacrifice.

Liturgical “participatio” must therefore be understood as a grace from Christ who “always associates the Church with Himself” (Sacrosanctum Concilium, 7). He is the one who has the initiative and the primacy. The Church “calls to her Lord, and through Him offers worship to the Eternal Father” (no. 7).

The priest must therefore become this instrument that allows Christ to shine through. As our Holy Father Pope Francis recalled recently, the celebrant is not the host of a show, he must not look for sympathy from the assembly by setting himself in front of it as its main speaker. To enter into the spirit of the Council means, on the contrary, to be self-effacing, to refuse to be the center of attention.

Contrary to what has sometimes been maintained, and quite in keeping with the conciliar Constitution, it is altogether appropriate, during the penitential rite, the singing of the Gloria, the orations and the Eucharistic prayer, that everyone, priest and faithful, turn together toward the East, so as to express their intention to participate in the work of worship and redemption accomplished by Christ. This way of celebrating could possibly be implemented in cathedrals, where the liturgical life must be exemplary (cf. no. 41).

Of course, there are other parts of the Mass in which the priest, acting “in persona Christi Capitis” [“in the person of Christ the Head”] enters into a nuptial dialogue with the assembly. But the only purpose of this face-to-face is to lead to a tête-À-tête with God which, through the grace of the Holy Spirit, will become a heart-to-heart conversation. The Council thus proposes other means of promoting participation: “acclamations, responses, psalmody, antiphons, and songs, as well as by actions, gestures, and bodily attitudes” (no. 30).

Retrieved August 21, 2015 from http://www.catholicworldreport.com/Item/3947/silent_action_of_the_heart.aspx