Pope Francis officiates during Benedict's burial as pilgrims throng to the Vatican.

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In a first for the modern Catholic Church, Pope Francis presided over Pope Emeritus Benedict XVI's burial mass on Thursday in honour of his friend and retired predecessor.

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In 2013, Benedict, who passed away on Saturday at the age of 95,

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shocked the faithful by stepping down as the first pope to do so in more than 600 years.

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According to church academics, his funeral marked the first time a supreme pontiff presided at the previous pope's funeral in modern times.

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On Thursday morning, a large crowd assembled in St. Peter's Square.

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Before the last of the morning fog had burned off the dome of St. Peter's Basilica, where Benedict had laid in state, the funeral procession started.

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Moments after Benedict's casket was brought into the Piazza, the liturgy started at 9:30 a.m. local time.

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 In a wheelchair, Francis arrived. Francis began his sermon by quoting from Jesus' final words as he hung on the cross: "Father, into your hands I surrender my spirit.

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 The spirit of life, Francis said in Italian, "quietly inspires us," and it "wants to mould the heart of every pastor, until it is attuned to the heart of Christ Jesus."

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