On Sept. 21, Pope Francis will mark the 60th anniversary of a secret encounter that not only changed the trajectory of one young chemist’s life, but eventually ecclesiastical and world history.

On Sept. 21, 1953, a 16-year-old boy named Jorge Bergoglio was planning to go out to celebrate with friends an Argentinian national holiday called Students’ Day, which is always held on the first day of spring in the Southern Hemisphere.

Jorge decided to start the holiday by going to pray at his parish church dedicated to St. Joseph.

He likely was unaware that, in the Church’s liturgical calendar, Sept. 21 is the feast of St. Matthew, the despised tax collector who, despite his sins, was nevertheless shockingly summoned by the Lord to become one of his apostles.

When Jorge arrived at church, he saw a priest he didn’t recognize but who seemed to radiate holiness. He decided to approach him and asked him to hear his confession.

We don’t know what Jorge said to the priest or what the priest said in response. But we do know that that confession totally changed not only the teenager’s plans for the day, but for the whole course of his life.

Meeting with 200,000 exuberant members of ecclesial movements in May for the vigil of Pentecost, Pope Francis shared some of his memories of this pivotal event in his vocation story.

"For me, this was an experience of encounter: I found that Someone was waiting for me. Yet I do not know what happened. I can’t remember. I do not know why that particular priest was there, whom I did not know, or why I felt this desire to confess. But the truth is that Someone was waiting for me. He had been waiting for me for some time. After making my confession, I felt something had changed. I was not the same. I had heard something like a voice or a call. I was convinced that I should become a priest."

He gave some extra details in 2010, in a book-length interview with Sergio Rubin.

"In that confession, something very rare happened to me. I don’t know what it was, but it changed my life. I would say that I was caught with my guard down. … It was a surprise, the astonishment of an encounter. I realized that God was waiting for me. From that moment, for me, God has been the one who precedes [to guide me]. … We want to meet him, but he meets us first."

Sixty years later, Pope Francis still seems astonished at the significance of this encounter, the reality of a God who awaits us with the love of the father of the Prodigal Son, anticipating his beloved child’s return.

"We say we must seek God; go to him and ask forgiveness," Pope Francis told the members of the ecclesial movements in May. "But when we go, he is waiting for us; he is there first! In Spanish, we have a word that explains this well: primerear — the Lord always gets there before us; he gets there first; he is waiting for us! To find Someone waiting for you is truly a great grace. You go to him as a sinner, but he is waiting to forgive you. … When we seek him, we discover that he is waiting to welcome us, to offer us his love. And this fills your heart with such wonder that you can hardly believe it, and this is how your faith grows — through encounter with a Person."

During that sacramental conversation with the priest, Jorge realized that the merciful God who had been waiting for him and who had come to meet him through the priest’s ministrations was calling him to be a priest.

Just as much as Jesus had summoned Matthew to become an ambassador of the salvation from sins to his friends and the whole world, the same Lord was calling the adolescent Jorge to be an emissary of that patient Divine waiting and merciful reconciliation to others.

After a new springtime erupted in his soul, Jorge decided not to go to the train station to meet his friends, but returned home, pondering the mystery and meaning of his call.

He told Sergio Rubin that he still retains in his breviary a lengthy personal credo he wrote before his priestly ordination, in which he affirmed, "I believe in my history — which was pierced by God’s look of love, on the first day of spring, Sept. 21 — he came to meet me and invited me to follow him."

Just how much that vocational encounter and piercing look of love continues to influence Pope Francis’ daily life can be seen in his papal motto, "Miserando atque Eligendo," meaning, literally in Latin, "by having mercy, by choosing him." It comes from a commentary by St. Bede the Venerable on Christ’s call of Matthew, which is read in the Office of Readings on Sept. 21. St. Bede wrote, "Vidit publicánum et, quia miserándo atque eligéndo vidit, ait illi: Séquere me": "He saw the tax collector, and, because he saw him through the eyes of mercy and chose him, he said to him: ‘Follow me.’"

As Father Bergoglio pondered in the breviary each Sept. 21 St. Bede’s reflections on St. Matthew’s call, the seventh-century English saint’s words about the connection between God’s mercy and the priestly calling seems to have taken on autobiographical significance.

"By an invisible, interior impulse flooding his mind with the light of grace," Bede wrote, "he taught him to walk in his footsteps."

St. Matthew followed that path all the way to heaven.

Jorge Bergoglio has been following in those footsteps now for 60 years.

As we pray for him on the anniversary of this seminal day in his life, we should also open ourselves up to the reality Pope Francis is seeking to communicate to us by his motto, his witness and his words.

"The Lord never tires of forgiving: never!" Francis told us in his first Sunday homily as pope. "It is we who tire of asking for his forgiveness. Let us ask for the grace never to tire of asking for forgiveness, because God never tires of giving his forgiveness."

And in indefatigably waiting for us with love to give us that mercy, God reveals to us at the same time our vocation. He forgives and calls us to holiness and mission by a single, loving, soul-piercing glance.

Father Roger Landry is pastor of St. Bernadette parish in Fall River, Massachusetts,

and is national chaplain of Catholic Voices USA. He provided commentary for EWTN

during the conclave that elected Pope Francis.