It hurts, just a little, to refer to the London Olympics in the past tense. We waited so long for the Games, and then they came along, and they were completely brilliant, and now they are gone.
Vivid memories linger, fresh enough to feel like they don't yet belong to history. My own favourite moment had nothing to do with sport and lasted about twenty minutes. It was the first section of the opening ceremony, the thrilling industrial sequence in which Kenneth Brannagh as Isambard Kingdom Brunel read Caliban's dream speech and Glastonbury Tor was ripped up in a re-imagining of the industrial revolution.
That magical bit of theatre had one vital literary source. Danny Boyle and his writing collaborator Frank Cottrell Boyce were inspired by a strange and wonderful book called Pandaemonium, which is reissued this month after many years in out-of-print obscurity.
It was written by Humphrey Jennings, the outstanding wartime documentary-maker who captured a nation quietly coping under siege in films like London Can Take It!, A Diary For Timothy, and Listen to Britain. His great unfulfilled post-war obsession was Pandaemonium: an inviting assembly of short texts and illustrations capturing the wonder and upheaval of the industrial age.
The extracts (he called them "images") are contemporary accounts by poets, diarists, politicians, scientists and manufacturers, carefully arranged for theme and mood, like one long, unrealised documentary film script. The book was eventually finished after his death by Jennings' daughter Marie-Louise and published in the 1980s.
I spoke to Cottrell Boyce about how Pandaemonium came to play such an important role in the Olympic spectacle. "I bought Danny a copy when he was doing Frankenstein at the National Theatre and he loved it," he recalled. "As we were all coming up with ideas (for the opening ceremony) everyone was always picking it and finding something there. The opening section of the opening ceremony is actually like a condensed version of the book.
"Danny is always looking for that visceral experience and I suppose what was so attractive about Jennings' book is that there's no attempt at analysis, no attempt to settle the subject. It's simply...this is what it felt like to work in the mills, this is what it felt like to invent the spinning jenny. It's a series of feelings, all very excitable feelings. It was only later we thought, 'Gosh, we sort of made the movie that was in Jennings' head, in a weird way'."
If all this sounds stirringly upbeat, Jennings' notes for Pandaemonium also show a mournful ambivalence about the passing of a more gentle time. According to Cottrell Boyce: "I think he did see the bad in such upheaval, but often our best work exceeds our own opinions.
"What I responded to, as much as the anxiety and the pain, was the excitement of the industrial age. Jennings was living after the Second World War and he'd seen the very worst of technology, whereas we live in a slightly brighter age, technology-wise, when we think it could be the solution to various problems.
"I think it was Danny's genius to alight on the industrial revolution, something that contains all those contradictions, but does show us as a very vibrant, creative, go-ahead people."
What did Cottrell Boyce make of the political reaction to the opening ceremony? Some sneered at the "multicultural crap". Others saw the celebration of the NHS as vindication of anti-cuts protest.
"Well, people said all sorts of strange things about it. Our slogan was 'This is for everyone'. For me, our great achievement was creating something where everyone liked something in there. You don't really want it pulled down to one faction. The Jarrow marchers and suffragettes are in there, but it's also the most affectionate portrait of the monarch we've ever had.
"I'm loathe to align it - and I know Danny is - to any one perspective. I want to remember what it felt like on that night, and I remember people felt very together and included."
Jennings' daughter Marie-Louise is pleased at the prospect of new people discovering more of her father's work now Pandaemonium has the chance to reach a wider audience. I asked her why he remains an important cultural figure.
"Before him the working classes were treated as a kind of joke in film and documentaries - the cheery bus driver and so on," she said. "They were not treated as people with their own voices, views, needs and rights...His wartime films still speak for us, because they allowed us a voice. You don't really you see the enemy, or images of war, at all - they are about the people."
Like the rest of us, Jennings' daughter watched the opening ceremony in wide-eyed amazement. The family connection did not immediately dawn until soon after, when her own daughters told her of Pandaemonium's part in Boyle and Cottrell Boyce's staggering presentation.
"I thought it was absolutely wonderful. I think it did capture the book, especially the early part of it...My father was a patriot, very much so. It was love of country connected to love of the people. And I think that came through at the opening ceremony."
Pandaemonium 1660-1886: The Coming of the Machine as Seen by Contemporary Observers is available now, published by Icon Books, £16.99