A couple of months ago, I visited Rome to research a novel. Much of the action is set in and around the Vatican and I spent a lot of time criss-crossing St Peter's Square. Each time I did so, I paused to stare up at the Pope's sixth floor apartment, hoping to catch a glimpse of the man himself: the Vicar of Christ; the Holy Father; Pontifex Maximus ... Old Red Socks.
Maybe I would chance upon him standing there at the window, cup of espresso in his hand, munching toast or enjoying a glass of wine. But no such luck.
The thing is, it's a full-time job being head of the Holy Catholic and Apostolic Church. You don't get time off. Benedict XVI may be the ultimate authority on faith and morals, but that doesn't mean he can do as he likes.
He never gets to go to the movies.
A pizza with friends at that nice little joint near Santa Maria Maggiore? I don't think so. And when, I wonder, did the Pope last take the train to his hometown in Bavaria just to catch up with family?
But there are compensations. The Pope's visit to New York and Washington, which concluded on Sunday, was a huge success.
Even non-Catholics, President George W Bush included, were impressed. The big surprise was how warm and informal he was.
He was the Disney version of your favourite grandfather — white haired, twinkly eyed, making time for the children and the disabled, doing his best to be interested in everything that was said and everyone who reached out to him.
How times change! When Benedict was plain old Cardinal Ratzinger — not a name destined to endear one to the faithful — he was a bit of a holy terror. It wasn't only his unfortunate past, most obviously his membership of the Hitler Youth and his year in the Wehrmacht, fighting the Russians.
It was also the fact that he had spent years as Prefect of the Congregation for the Doctrine of the Faith (formerly the Inquisition, or Holy Office). In this latter role, he was known to be a hardline conservative, implacable in his opposition to birth control, abortion, gay marriage and all other manifestations of liberal — ie aberrant — thinking. Even when he was elected Pope, he found it difficult to shake off some of his more fundamentalist opinions.
His speech in Regensburg in 2006, in which he quoted, with apparent approval, the opinion of a 14th century Byzantine emperor, to the effect that Islam was 'evil and inhuman', caused uproar in the Muslim world. Benedict had to row back on his verdict with all possible speed, insisting that he meant no harm and never intended to endorse the emperor's 'mistaken' views.
The naivety was breathtaking. Like many intellectuals before him, Benedict hadn't grasped the fact that words spoken to one, select audience might resonate quite differently elsewhere.
Since that watershed moment, he has concentrated much more on the pastoral dimension of his work, and it was this that was most conspicuous during his American visit.
At a youth rally in St Joseph's Seminary in Yonkers, he worked the crowd with consummate skill and, you would have to say, grace.
He was particularly good with the many disabled children brought to meet him, as well as with the young seminarians for whom this was their first contact with the church's CEO.
He visited Ground Zero, the site of the former World Trade Center, offering his blessing and speaking with relatives of some of those killed during the attacks of September 11, 2001.
He offered the first Papal mass in St Patrick's Cathedral on Fifth Avenue; addressed worshippers in one of the city's leading synagogues, whose rabbi is a Holocaust survivor; and presided over open-air Masses in the baseball stadia of the Washington Nationals and the New York Yankees.
Most significantly, he apologised over and over again for the child sex abuse scandal that has so shaken the Church in recent years.
This is a subject he should have tackled openly years before, when as Dean of the College of Cardinals he was Pope John Paul II's right-hand man. But better late than never. At least no one, including those most intimately affected, doubted his sincerity.
In fact, I don't think I heard a word of criticism throughout his visit.
He played a blinder. Everyone thought it was just great that the Pope was in town. They loved him. Hands reached out to him wherever he went. His smile and gentleness struck home.
Even his voice, with its marked Bavarian accent, was soft and welcoming.
As a lapsed Presbyterian myself, I say, well done, Sir. The papacy of Benedict XVI may not be as monumental, or as long, as that of his Polish predecessor.
But as Servant of the Servants of God, this German pontiff will also leave his mark.