People like to bang on about "Glastonbury moments" – those transcendent, communal instants where band, weather and public drunkenness merge in beautiful harmony.
It's largely a myth, of course: you're just as likely to experience a Glasto epiphany while whazzed off your margin in the Healing Fields than you are down the front at the Pyramid.
Even so, last night (June 26) Muse provided a moment that few here will ever forget: an extraordinary, crowd-engulfing version of U2's 'Where The Streets Have No Name', featuring The Edge on guitar.
That tick-tocking intro riff was made for giant events like this. According to Bono, U2 were planning to open with it – you can easily imagine how immense their set would have been, had they not been forced to cancel.
If only the rest of Muse's performance had been as thrilling. It's interesting that The Edge joined them onstage, because U2 and Muse have a lot in common.
Both bands tread the tricky fine line between anthemic grandeur and outright hollow bombast (and both bands have been creeping more towards the latter on recent albums).
Indeed, it's tempting to speculate whether or not Muse – the ultimate grandstanding, big-gesture rock act – could even have existed without U2.
Special guest aside, it was hard not to feel a sense of over-familiarity about Muse's set. They last headlined Glastonbury in 2004, and there was nothing especially different about this performance, in terms of visuals.
There can be few festival-goers who haven't witnessed a Muse headline set in the last few years.
And even though the trio made the odd attempt to keep things fresh – Matt Bellamy injected a new, Eddie Van Halen-esque solo into 'New Born', they dropped in an early B-side ('Nishe'), and bassist Chris Wolstenholme smoked a pipe, for some reason – this was essentially Muse doing what Muse always do: dispatching the hits with virtuosity and crisp efficiency.
The audience went apeshit, of course. They always do with Muse. Which is a puzzle, because the band don't really do anything to encourage such an impassioned response.
There's always been something weirdly detached and remote about them, live. There's no banter, no connection.
That was fine when they were riding high on the hook-packed brilliance of 'Black Holes And Revelations'. But their most recent album 'The Resistance' hasn't captured the public imagination in the same way.
And the yawning, bloated likes of 'Guiding Light', last night especially, made me yearn for the spry, venomous rock act who gave us 'Cave' and 'Fillip' a decade ago.
There is, let's not forget, something miraculous about the fact that a band this heavy, this unique, has been embraced so passionately by the mainstream.
But you do get the feeling Muse are at a crossroads. Their music can't possibly get any bigger or more grandiose. The levels are all maxed out.
Perhaps it's time they took their foot off the accelerator and wrote something more heartfelt, more personal, and on a human scale.