The Holy Father, it has been reported, walked with a black stick (well, he could hardly have used a white one, that really would have hit the headlines) for about 100 yards to an Alitalia plane from the helicopter which flew him from the Vatican to Leonardo da Vinci airport on his way to Mexico. But he coped with the steps of the aircraft unaided and then flew across the Atlantic on a 13 hour and 30 minutes flight. This isn’t the first unavoidable sign that he seems to be getting older (he is 85, after all); a few months ago, he started using a wheeled platform rather than walk down the vast length of St Peter's Basilica to the altar. So of course, we now have the beginnings of the chatter, usual at about this stage in a modern pontificate (in Italy at least), of the possibility of his retirement. It will all, of course, come to nothing. Popes don’t retire. But why not? It’s worthwhile to ask why the notion of Benedict XVI’s retirement is just as unthinkable as that of John Paul II was, even though the more infirm the late pope became, and the more obvious it was that he just wasn’t going to retire, the more the question was canvassed. In one way he gave the answer himself: for, the more he suffered, the clearer it became that his very suffering was a powerful offering to God and his Church. I hope I will be forgiven if I quote from something I wrote myself at the time (for memories are short) as we all approached the 25th anniversary of his enthronement: