We prayed at the graves of saints whose names are so familiar in the Church’s liturgy: Peter and Paul, Lawrence, Cecilia, Agnes, Clement, and many others.

We saw the ancient tomb of Peter and attended an audience with his successor, Benedict XVI. Each day we celebrated the Eucharist in a different place rich with centuries of Christian faith.

And throughout the journey we discovered a city genuinely layered with our Catholic history, woven concretely throughout the modern city, constantly reminding us not simply of our fascinating Catholic history, but even more, of the communion of saints, the great cloud of witnesses who have gone before us and remain as models for us.

This is the fundamental value of a pilgrimage to Rome. Each place we visited, each thing we saw, was a concrete reminder, a physical connection to those communities of Christians, from across two millennia, who believed as we believe, struggled to live faithfully in the world as we struggle, and found their hope and joy in Christ as we do.

One day we celebrated Mass deep in the catacombs of St. Callixtus, where we were literally surrounded by the saints, those brothers and sisters in faith who were buried there more than 1,600 years ago, and whose remains still rest in the catacombs. In the same way that a visit to St. Peter’s Basilica, filled with pilgrims from around the world, powerfully reminds us of the great breadth and diversity of Christ’s body in our own time, so celebrating the Eucharist in the catacombs powerfully reminded us of our communion with Christ’s body across time.

Many of those early Christians died for their faith, for believing what we believe. It is a compelling reminder of the gift and strength of God’s love, and of his call to all Christians to witness to him, not counting the cost.

If much of our pilgrimage served to deepen our sense of Catholic Christian identity broadly, there were also experiences which encouraged and challenged us in ways particular to those preparing for priesthood.

One brief experience keeps coming to my mind. In the portico of the church of Santa Maria in Trastevere, one of the most ancient in Rome, the walls are imbedded with the fragments of grave markers engraved with the names of early Christians.

One in particular caught my eye. In poorly-chiseled letters it read, simply: “Lukus, Presbyter.”

In the earliest centuries, likely during the time when the Church was still a persecuted minority in the Roman Empire, this man served as a presbyter, a priest, of the Church. He gave up his entire life, put his life in danger, to serve the Body of Christ as one whom God had called to ordained ministry.

He answered that call, knowing the potential consequences, and lived it to his death. And to this day we know that in ancient Rome a man named Luke answered God’s call to the priesthood. He may have been martyred; he may have died in his sleep.

But he was willing to give all to serve the people of God and aid in the work of the whole Church to witness to the gospel of Christ. And on that May afternoon, he continued to witness very powerfully to at least one seminarian.

For all Catholic Christians, a pilgrimage to Rome is a powerful, enriching reminder of where we have come from, who we are, and how connected we are to that great cloud of witnesses, the communion of saints.

It is a reminder both of the joy and of the cost of discipleship, of the responsibility of all Christians to bear witness to the gospel in a world that desperately needs to hear it.

And for those of us in formation for the priesthood, it was a compelling encouragement to continue to discern God’s call to the priesthood, to be formed to serve Christ and his Church with the whole of our lives, just like Luke the Presbyter.