When Benedict XVI agreed to publish his collected works, it came as no surprise that he decided that the first volume to be published should contain his writings on liturgy.

As he himself states in his “Introduction” to that volume: “The liturgy of the Church has been for me since my childhood the central reality of my life, and it became the center of my theological efforts.”

In that same “Introduction” the Pope emeritus commented on the Vatican Council’s decision to issue as its first document the Constitution on the Sacred Liturgy, Sacrosanctum Concilium.

From one point of view this was due to the relatively satisfactory nature of the preliminary document which the fathers of the Council received and further developed and elaborated. But from a deeper perspective, Benedict writes, it represents the Council’s providential confession of “God’s primacy,” of “the absolute precedence of the theme of God.”

Central to the pope emeritus’s writings on liturgy is this fundamental conviction: The priority and primacy of God’s action. Catholic liturgy celebrates what God has done and is doing for humanity through and in Jesus Christ.

Benedict stresses again and again in his theological writing the theme of “semel” and “semper.” Jesus Christ’s redemptive sacrifice has occurred once and for all, semel: Outside Jerusalem when Pontius Pilate was Roman procurator and Caiaphas was High Priest. But it endures, semper, as the eternal sacrifice of God’s only-begotten.

It is this definitive self-gift of God’s Son that is made present at every Eucharist. Liturgy actualizes the saving events wrought by God in Jesus Christ, making participants contemporaries and beneficiaries of Christ.

Throughout his theological and episcopal ministry, Benedict has been a fervent proponent of what the Constitution on the Sacred Liturgy urges: The “active participation” (participatio actuosa) of all the faithful in the liturgical celebration.

But he insists that such participation goes far deeper than merely a distribution of external tasks: Greeting, reading, singing – however indispensable these services are. It requires much more of us: Namely, a profound appropriation of the central action of the liturgy. We are called to participate ever more fully in Jesus Christ’s paschal mystery.

A somewhat disputed element of the pope emeritus’s liturgical writing has been his advocacy of Eucharistic celebration “ad orientem:” Priest and people together facing the East.

In a telling comment in the “Introduction” to his collected writings on liturgy, Benedict concedes that he had seriously considered omitting the few pages of The Spirit of the Liturgy propounding this view, so badly had his proposal been misunderstood.

But he decided to retain them, because the central point was not primarily a geographical turning to the East, a reorientation of altars. Rather his concern has ever been a reorientation of hearts, a spiritual turning to Christ. Hence a con-versio ad Orientem: an ever-renewed turning to the Sun of Justice, Jesus Christ.

Many have rightly called attention to the influence exerted upon the pope emeritus by the theology of Saint Augustine. But, re-reading The Spirit of the Liturgy, one is struck how much he resembles the first great systematic theologian of the Church: Saint Irenaeus of Lyons.

Like Irenaeus, Benedict’s theological vision is profoundly “materialistic,” inherently “somatic” and sacramental. Perhaps this is why, like his friend and mentor, Henri de Lubac, he treats with respect the thought of Teilhard de Chardin. In Benedict’s vision matter is not denied, but transfigured.

The senses are not spurned, but transformed. Bodily gestures are not adventitious, but constitutive and formative. Indeed, the whole material cosmos is intimately implicated in what transpires upon the altar.

And all this because the very heart of the matter is the resurrection of Jesus Christ. Jesus does not rise a disembodied soul, but bodily. Body transformed in the power of the Spirit – what Saint Paul calls soma pneumatikon (1 Cor 15:44).

Body bearing wounds of victimhood, yet rendered glorious by being saturated with God’s love and forgiveness. Body not self-contained, but totally relational, totally gift, really present in Eucharist, poured out to embrace a humanity called to transfiguration.

In a programmatic article, dating from 1967, the young Joseph Ratzinger wrote:

“All Christian theology, if it is to be true to its origins, must be first and foremost a theology of Resurrection. It must be a theology of Resurrection before it is a theology of the justification of the sinner; it must be a theology of Resurrection before it is a theology of the metaphysical Sonship of God. It can be a theology of the Cross, but only as and within the framework of a theology of Resurrection. Its first and primordial statement is the good tidings that the power of death, the one constant of history, has in a single instance been broken by the power of God and that history has thus been imbued with an entirely new hope. In other words, the core of the gospel consists in the good tidings of the Resurrection and, thus, in the good tidings of God’s action, which precedes all human doing.”

One discerns here a magisterial echoing of Paul’s decisive insistence: If Christ Jesus is not risen, both preaching and faith are vain, mere delusions (1 Cor 15:14).

Forty years later, preaching at the 2007 Easter Vigil, Benedict XVI would proclaim this Easter Gospel once again. Exercising his Petrine responsibility, he prayerfully confirms his brothers and sisters in the apostolic faith:

“In the resurrection of Jesus, love has been shown to be stronger than death, stronger than evil. Love made Christ descend, and love is also the power by which he ascends. The power by which he brings us with him. In union with his love, borne aloft on the wings of love, as persons of love, let us descend with him into the world’s darkness, knowing that in this way we will also rise up with him. On this night, then, let us pray: Lord, show us that love is stronger than hatred, that love is stronger than death. Descend into the darkness and the abyss of our modern age, and take by the hand those who await you. Bring them to the light! In my own dark nights, be with me to bring me forth! Help me, help all of us, to descend with you into the darkness of all those people who are still waiting for you, who out of the depths cry unto you! Help us to bring them your light! Help us to say the “yes” of love, the love that makes us descend with you and, in so doing, also to rise with you. Alleluia. Amen!”

On the occasion of his ninetieth birthday, his fellow believers gratefully join Benedict’s faith-filled acclamation: “Alleluia. Amen!”

Father Robert Imbelli, a priest of the Archdiocese of New York, is the author of Rekindling the Christic Imagination: Theological Meditations for the New Evangelization