Addressing more than 20,000 people gathered today in St. Peter's Square, the Holy Father explained that his name was inspired by the wartime Pope as well as by St. Benedict of Nursia, father of Western monasticism.

On a sunny morning in Rome, Benedict XVI arrived in Pope John Paul II's old, open-air white jeep. He was driven around the square for some 15 minutes to greet pilgrims up close.

His first words were to express his "awe and gratitude to God, who surprised me first of all, in calling me to succeed the Apostle Peter."

Seated in a chair, without a canopy to protect him from the sun, Benedict XVI confessed his "interior trepidation before the enormity of the task and responsibility that have been entrusted to me," for which he requested the "insistent prayer" of believers.

The Holy Father was serene and smiling during the more than two-hour audience, greeting the faithful, including more than 1,000 Germans, with his hand or a blessing, in response to their cries of encouragement.

The former Cardinal Joseph Ratzinger recalled the figure of Benedict XV, whose pontificate spanned 1914-1922, as "a courageous and authentic prophet of peace" who "did his utmost with strenuous courage from the start to avoid the drama of war and then to limit its inauspicious consequences."

"Following his footsteps," Benedict XVI said, "I wish to put my ministry at the service of reconciliation and harmony among men and nations, profoundly convinced that the great good of peace is, first of all, a gift of God, a fragile and precious gift to be invoked, defended and built day after day with the contribution of all."

The Pope explained that his name also evokes St. Benedict of Nursia (480-547), founder of Western monasticism and patron of Europe together with Saints Cyril and Methodius.

"The gradual expansion of the Benedictine Order founded by him has had an enormous influence on the spread of Christianity on the whole continent," he said. "Because of this, St. Benedict is much venerated in Germany and, in particular, in Bavaria, my native land."

The saint, the Pontiff continued, "constitutes a fundamental point of reference for the unity of Europe and a strong reminder of the inalienable Christian roots of its culture and its civilization."

With his pontificate, the Holy Father said he wishes to leave Christians the same message that St. Benedict left his monks in Chapter 4 of his monastic Rule: "Prefer absolutely nothing to Christ."

"At the beginning of my service as Successor of Peter, I pray to St. Benedict to help us to hold firm the centrality of Christ in our life. May he always be first in our thoughts and in all our activity," the Pope affirmed.

At the audience the Holy Father had the surprise of receiving a large pilgrimage from the Archdiocese of Spoleto-Nursia, accompanied by Archbishop Riccardo Fontana.

Benedict XVI announced that in the upcoming general audiences he will continue with the commentaries on the Psalms and canticles of vespers that Pope John Paul II had prepared and that were suspended after Jan. 26 because of his illness. He died April 2.

The Pope greeted pilgrims in several languages. He surprised many by perfectly reading a brief greeting in Polish.

After the audience, all the cardinals and bishops present in St. Peter's Square went up to greet the Pope personally and to exchange some words with him in private.

The audience concluded with the Pontiff's blessing imparted before the singing of the Our Father in Latin. With a gesture of his hands, the Holy Father encouraged all those present to sing it.