"Roger Federer as Religious Experience" is how David Foster Wallace, a late American author, described watching the Swiss, and nowhere is there greater love for the Swiss than on Wimbledon's Centre Court. Love is the right word here; affection doesn't seem quite strong enough to describe the crowd's feelings for a player who is now just two matches away from becoming the first man to win eight Wimbledon titles.
Back home in the cantons, there's a Swiss restraint towards Federer; to encounter the most fanatical of Federer's supporters - there are entire families here walking around in baseball caps with the 'RF' logo on the front - you have to come to south-west London. Take the District Line to Southfields, stroll to the All England Club and you're travelling deep into Federer territory. This is where Federer scored his first grand slam title, in 2003, and seven of his 17 majors were won here, with each of those seven bringing a lot of pleasure to a lot of people.
But are even those most devoted of Federer-philes wondering whether this is his last great opportunity to win Wimbledon? And by extension, since this is the grand slam tournament best suited to Federer's talents, that this could be his last chance to win one of the four majors?
The neutral observer would contend that Federer, who turns 33 next month, may never again be so well-placed to cuddle that golden trophy with the pineapple-shaped top. If this tournament has shown us anything, it's that the new generation have arrived to threaten the tennis establishment. Two of the semi-finalists, Milos Raonic and Grigor Dimitrov, will be making their first appearances at this stage of a grand slam, and they are bound to be even better next summer.
The same applies to Nick Kyrgios, an Australian wild card who defeated Rafa Nadal in the fourth round to make the quarter-finals of a major for the first time. This summer, the semi-finals are a split between the old and the new, with Federer to play Raonic and Djokovic to meet Dimitrov. Never again, you suspect, will Federer and the other members of the Big Four have it all their own way on these lawns.
It was two years ago that Federer won his last grand slam title here, with victory on Centre Court over Andy Murray. Outside southwest London, Federer's last slam title came four and a half years ago at the 2010 Australian Open. There's no doubt that conditions at Wimbledon are slower than they used to be, but Federer's attacking game is better rewarded here than it is on the hard courts of Melbourne and New York, and certainly better than on the clay of Roland Garros.
Eleven years after winning that first Wimbledon title, and now a father of four after his wife Mirka gave birth to a second set of twins in May, Federer is still trying to improve, and the indications are that employing Stefan Edberg as his coach has made him a more commanding presence in the service-box. Over four sets during the all-Swiss quarter-final against Stan Wawrinka, Federer visited the net 45 times, winning 32 of those points.
And what a victory it would be if Federer could pull it off this week. If Federer were to defeat Raonic on Friday, and then beat Djokovic or Dimitrov on Sunday, he would move past Pete Sampras - they currently share the Wimbledon record with seven titles each.
We should also consider the leaderboard for all grand slam titles. After Nadal's success at the French Open last month - he is the only man to win the same major nine times - the Majorcan moved to 14 slams, cutting the gap between him and Federer to just three. Barring career-ending knee trouble, you would have to imagine that Nadal will win at least a couple more in Paris during his years. That tournament alone could propel Nadal to 16.
Winning this Wimbledon title, and pushing his total from 17 to 18, could determine whether Federer protects his position as the pre-eminent tennis player of this and all generations.
It's seven years since Federer's last victory over Nadal at a grand slam tournament - that came in the 2007 Wimbledon final. So Nadal's fourth-round defeat to Kyrgios certainly didn't do Federer, who had been projected to play the Spaniard in the semi-finals, any harm. On his ninth appearance in a Wimbledon semi-final - he won all of the previous eight - he will be playing an opponent, Raonic, who has never been that deep into a major before.
Let's not also forget that Djokovic hasn't won a grand slam for a while - you have to spool back a year and a half, to the 2013 Australian Open, for his last tournament victory. He has been reaching slam finals, it's just that he hasn't been winning them.
Federer might never have an opportunity like this again.
Mark Hodgkinson is the author of Lendl: The Man Who Made Murray. Hodgkinson is writing daily pieces for ESPN during Wimbledon.