VATICAN CITY (AP) — Pope Francis paid a heartfelt tribute Friday to his predecessor Benedict XVI, saying his faith and teaching had "enriched and invigorated" the Catholic Church and would remain its spiritual patrimony forever.

Francis offered the respects during an audience with the cardinals who elected him to succeed Benedict, whose resignation set in motion the extraordinary conclave that brought the first prelate from the New World and first Jesuit to the papacy.

Francis, 76, tripped and stumbled when he greeted the dean of the College of Cardinals, Cardinal Angelo Sodano, at the start of the audience, but he recovered immediately.

Speaking at times off the cuff, Francis said Benedict had "lit a flame in the depths of our hearts that will continue to burn because it is fueled by his prayers that will support the church on its missionary path."

"In these years of his pontificate, he enriched and invigorated the church with his magisterium, his goodness, guide and faith," Francis said. Pausing for effect, he added: "His humility and his gentleness."

Francis has said he wants to visit Benedict at the papal residence in Castel Gandolfo where he has been living since Feb. 28, when he became the first pope in 600 years to resign. No date has been set for the visit. Francis is due to be installed as pope on Tuesday.

The relationship between the two pontiffs has been the subject of intense speculation given the novelty of soon having a retired and reigning pope living side by side. Some analysts have expressed concern about the influence Benedict and his loyalists might wield over the new pontificate, or worse how certain factions in the church might try to undermine Francis' authority by continuing to use Benedict as their reference point.

The presence of Benedict's closest aide, Archbishop Georg Gaenswein, at all of Francis' inaugural events has confirmed some crossover; Gaenswein is also the head of the papal household, meaning he has an important role to play in the transition and Francis' day-to-day schedule.

In fact, on Friday, Gaenswein accompanied Francis to the papal apartment in the Apostolic Palace, which has been sealed since Feb. 28. The seals were broken, Francis took the keys and opened the door, and Gaenswein hurried in to turn on the lights.

During Friday's audience, cardinals lined up and warmly greeted Francis, exchanging physical embraces with the new pope. U.S. Cardinal Timothy Dolan grasped Frances' shoulder as he chatted. Most if not all the cardinals then went to chat with Gaenswein, perhaps to inquire about Benedict.

On the first day of his pontificate, Francis's personal and liturgical style couldn't have come off as more different than that of Benedict: He went to his hotel to pick up his luggage, greet the staff and pay the bill, then delivered an off-the-cuff homily reminding his cardinals of the need to make the church strong.

The very pastoral acts were typical Francis. Benedict, while similarly humble and gentle, spent 30 years inside the Vatican, first as its doctrine chief and then as pope, where his homilies were dense theological treatises and his Masses were formal affairs in the pre-Vatican II style.

In his remarks Friday to cardinals, Francis noted that a good half of the men in the room were elderly, and he urged them to share the wisdom of their years with the young.

"Let us give this wisdom to young people; like good wine, it becomes better with age," he said. "Let us give to young people the wisdom of life."

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