Buoyed by enthusiastic, supportive and sometimes record crowds of worshippers in Switzerland, Pope John Paul II battled through debilitating ill-health to complete his first trip abroad after an eight month pause.
The airliner carrying the pope left an airbase near the Swiss capital Bern for Rome on Sunday evening, a Swiss Roman Catholic church spokesman said.
The 84-year-old pontiff's 32-hour visit to Bern was capped by a mass with 70,000 worshippers in a field on the edge of the Swiss capital on Sunday
Despite the controversy surrounding the wheelchair-bound pope's fitness to lead the Roman Catholic Church, the size of the crowd exceeded those the pontiff drew during his last visit to the country in 1984.
The mass was also the largest held in Switzerland for half a century, the Swiss Bishops Conference said, and followed a youth rally on Saturday which attracted 14,000 cheering young Roman Catholics.
After appearing drawn and silent on his arrival, John Paul told the youngsters they had given him a lift and he perked up again on Sunday, leading the mass on a semi-circular stage capped by a white dove of peace.
But he showed signs of exhaustion at the end of the day in a ceremony to thank former Swiss Guards, the group of Swiss military-trained Roman Catholics who traditionally form the Vatican's protection corps.
An aide intervened to read part of his prepared speech, which the pope later completed himself.
He expressed his "particular gratitude" to them, saying they had been an honour to Switzerland.
Despite being permanently limited in his movements, and sometimes straining to deliver prayers in three of Switzerland's national languages -- French, German and Italian -- John Paul blessed worshippers, waved to the supportive crowd and reacted to their applause during mass.
The pope launched a "pressing appeal for a commitment to unity for all Christians", amid some tensions between the Catholic and Protestant Church hierarchies in Switzerland, which is evenly divided between the two religions.
Only weeks after revelations of mistreatment in Iraqi jails, partly through a leaked report by the International Committee of the Red Cross, he also referred to Switzerland's "great tradition of respect for humankind" typified by the Red Cross, which is based in the country.
He noted the "indestructible dignity" of man and warned that "any outrage upon man is an outrage to his Creator".
The crowd included Swiss Catholics who had travelled from other parts of the country, and sizeable groups of people flying flags from east European countries, including Croatia and his native Poland.
John Paul's efforts to fight off the debilitating effects of Parkinson's disease drew the admiration of worshippers, who also remarked that he had kept his mental alertness.
"Of course he is not in very good condition, yet the courage and strength he showed yesterday are extraordinary. He was dynamic for a day and old age is a part of human nature," Hugues Moret, a 17-year-old student from Fribourg said.
"It is the only time in our life that we will see this personality, maybe the most popular in the world."
"He is like a guiding light in our religion, one mustn't lose this symbol," Moret added.
David Serrago, also a Swiss student, said: "He is suffering like Jesus on the cross, but he still has strength to continue. He must decide for himself."
The pope's visit was punctuated by long breaks in an old people's home in Bern run by Swiss nuns.
Vatican officials said the less intensive style of his Swiss trip would serve as a template for future journeys to meet the faithful.
Despite the enthusiasm of worshippers over the weekend, there has been considerable scepticism in Switzerland about the pope's ability to continue at the helm of the Catholic Church.
Three-quarters of Swiss questioned in a recent opinion poll felt he should retire, a feeling shared by a group of Swiss Roman Catholic theologians, priests and community leaders in a public letter to the pope.