Finally, we learned that despite his advanced age, Francis has a seemingly boundless reserve of energy.
Even before he left Rome, he had trimmed the two days of rest planned for Benedict XVI to one, adding a 150-mile outing to Aparecida, Brazil, on Wednesday to visit a famed Marian shrine, and later in the day stopping by a Rio hospital that treats alcohol and drug addicts.
On the plane en route to Brazil, he stood for an hour to chat with each journalist covering the trip, then spent the rest of the flight talking to his Vatican aides and making notes. A spokesman said nap time had been planned for the pope, but he never used it.
Even on his alleged day off on Tuesday, Francis kept at it. He held a business meeting with a cardinal from Honduras, Oscar Rodriguez Maradiaga, who's in charge of a new council of eight cardinals from around the world helping the pope with Vatican reform.
At one stage, a Vatican spokesman confessed, "I'm happy we're halfway through, because if [the trip] were any longer I'd be destroyed."
Despite the grueling pace, Francis seemed as fresh at the end as at the beginning. Nor will things slow down anytime soon, since he's already announced that he won't take the usual papal break in August, but will stay on the job in Rome.
The "Energizer bunny" aspect of his personality should serve Francis well, because his bravura performance in Brazil notwithstanding, the Vatican is not going to reform itself.
John L. Allen Jr. is CNN's senior Vatican analyst and senior correspondent for the National Catholic Reporter.