Make no mistake about it: persistent opposition to the changes in the liturgy that were authorized by the Second Vatican Council and approved by the late Pope Paul VI has had little or nothing to do with the quality of vernacular translations and liturgical music, nor with the sometimes free-wheeling style of some presider-celebrants. It has everything to do with ecclesiology.

The basic changes in the celebration of the Mass came about because theologians, liturgical scholars, and thousands of bishops and priests broadened their vision of the Church from a primarily hierarchical institution to the People of God.

Thus, when the priest was at the altar, with his back to the congregation, while reciting prayers in Latin in a barely audible manner, the message was clear, even if not explicit. The priest is the one who makes the Mass happen (the old textbooks referred to it as "confecting the Eucharist"), while the laity are present essentially as onlookers, fulfilling their weekly obligation to be present for the three main parts of the Mass: the Offertory, the Consecration and Communion.

The altar boys signaled the approach of the Consecration by the ringing of a small bell --- at the "Sanctus" (three rings), the "Hanc Igitur" (one ring), and the priest's genuflections before and after the elevations of the consecrated Host and chalice.

Some Catholics made no special effort to be at church in time for the start of Mass, because they knew that they had some leeway. The Offertory did not begin until the priest removed the chalice veil and the altar boys made a dash for the table containing the cruets filled with wine and water.

And no one left church before Communion, which was the third and last obligatory part of the Mass. Not to be present for all three parts of the Mass was tantamount to not fulfilling one's weekly obligation to "Keep holy the Sabbath." However, once the tabernacle door was opened and people began coming forward for Holy Communion, some headed for the exits and the parking lot.

The people in the pews were completely silent throughout the Mass, except for the children's Mass, when the young would be led in prayers and songs whose texts had no direct connection with those of the Eucharist itself.

There was no Offertory procession because the people had no role in presenting the gifts to be consecrated.

With the ringing of the bells, the congregation was stirred from day-dreaming, the perusal of the parish bulletin, or involvement in private devotions (relatively few "followed" the Mass with a missal). Ushers returned from the vestibule or from outside, where some had gone for a quick smoke.

The entire assembly would be hushed as the priest bent over the bread and the wine to bring God "down" on the altar through the recitation of the sacred words, "Hoc est enim corpus meum" ("For this is my body...") and "Hic est enim calix sanguinis mei" ("For this is the chalice of my blood...").

And then the coughing, the rumbling of kneelers, and a general sense of returning to ordinary time would shatter the reverential silence of the moment.

The rest of the service was almost anticlimactic. The priest recited the "Pater Noster" (the Lord's Prayer); there was no handshake of peace, not even for the altar boys, who then made their second dash to the cruet table to retrieve the Communion plates.

In some churches, the altar boys held the plates under the chins of the kneeling communicants while the priest distributed the sacrament, but in others the communicants handed the plate from one to another.

There was only the Post-Communion prayer, the blessing, the Last Gospel, and the prayers at the foot of the altar, for the conversion of Russia, that remained to be recited. The altar boy retrieved the priest's biretta; the celebrant brought down the re-covered chalice from the altar; and there was a short procession back into the sacristry. And that was that for another week.

To be sure, this was a completely valid Eucharist, although celebrated in a manner that gave very few people the idea that the congregation had anything essential to do with it. The Church was, for all practical purposes, the hierarchy and the clergy. Laity "belonged" to the Church for three purposes, as one British wag put it: to pray, to obey, and to pay.

It is the fundamental change in ecclesiology that is the real source of distress for opponents of liturgical reform, not simply the changes in words, rituals, and music. And that is why the stakes are so high in these so-called "liturgy wars."

Father Richard P. McBrien is the Crowley-O'Brien Professor of Theology at the University of Notre Dame.