Three years and nine months after his election, the first pope from the Americas continues to set a relentless pace as he reaches a milestone at which cardinals are ushered into semi-retirement.
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Francis has not ruled out following the historic example of his predecessor Benedict XVI, who retired, exhausted, in 2013.
But there is no suggestion that could happen soon.
Like almost every other day of his papacy, Saturday will be a working day for the holiday-phobic Francis: morning mass with cardinals followed by meetings with the Maltese president and a top Vatican official.
In the cerebral Benedict's place, Francis has brought an upbeat Latin tempo, a strong work ethic and the asceticism of a Jesuit missionary to the role of leading the world's largest church.
This will be the fourth birthday the former bishop of Buenos Aires has celebrated in the modest St Martha's boarding house he has made his home inside the Vatican's walls.
The world's 1.2 billion Catholics are, by now, used to the face Francis displays to the world.
More often than not it is one lit up by a crinkly-eyed, double-chinned smile, at official audiences and meet-and-greets where he displays his ease with people from all walks of life.
There are signs of fatigue, natural for a man of his age who lost part of a lung in his youth, and the occasional grimace bears witness to the sciatic pain that is a near constant companion.
Sometimes his features darken, usually indicating he is addressing issues dear to his heart: Europe's indifference to migrants drowning in the Mediterranean, the humiliation of the poor or, most recently, the destructive power of agri-business.
Born into a family of Italian heritage on December 16, 1936, Jorge Bergoglio became the 266th pope when he was elected on March 13, 2013. From the off he seemed like a man in a hurry. Several times he has implied he does not think he will be around for long.
He said he wanted "a poor church, for the poor". And more broadly his mission has been to recast the church as a compassionate institution, one that seeks to help believers with daily difficulties.
His first Jubilee year was dedicated to the theme of mercy, a quality Francis believes should be at the core of the church's work, rather than reflexes of condemnation and judgement.
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Faced with opposition, in the hierarchy and on the ground in the developing world, Francis has arguably made little headway in reshaping Catholic teaching. On vexed issues such as cohabitation and attitudes to homosexual or divorced believers in the church, reviews have ended with ambiguous conclusions that infuriated conservatives and disappointed radicals.
But the mood music has undeniably changed.
"Who am I to judge?" Francis asked when asked for his views on homosexuality, long seen as a disorder by the church.
Authorization to priests to absolve women who confess to having had abortions, a Jubilee initiative, has been extended indefinitely.
'Church is field hospital''
Bishops can now grant remarried divorcees communion on a case-by-case basis.
And the church recognizes that cohabiting couples might legitimately be prevented from marrying because of financial barriers.
Francis has also recognized the "erotic dimension of love" as a gift from God, while simultaneously trying to move Catholicism away from its obsession with sex.
And, by agreeing to examine the role of female deacons in early Christianity, some see Francis as having opened a door to the possibility of women clergy.
Pragmatic reformer rather than revolutionary, is a common assessment of the soon-to-be octogenarian.
"For him, the church is a field hospital, not a customs barrier," says Italian Vatican expert Marco Politi. "But he has not touched doctrine. He is not a progressive in that sense."
Marco Tosatti, another Vatican watcher, says Francis has "sown a lot of confusion inside the church".
"He's a journalists' pope. He's given the church a friendlier, lighter image. But summer sales do not attract new customers. The traditional Protestant churches tried adapting to the modern world and look at them: there's nobody left."
Politi says conservatives are biding their time.
"The goal is not a coup but to lay the groundwork for the eventual successor. Like the Tea Party that spent its time sabotaging Obama and found it was worthwhile when Trump was elected."
By Angus MacKinnon and Catherine Marciano