Michael Stipe took to the stage with Mike Mills, Peter Buck, and the very unrock and roll addition of a laptop. Throughout the gig, Stipe read lyrics from old and new songs alike from his laptop screen and cobbled together lyric sheets, and for an hour and a half REM were rough, ragged, under-rehearsed, and ultimately, absolutely magnificent.

For the first time in the 20-plus years they have been visiting these shores they truly rocked. Long ago we had 1995's overblown gig at Slane, and the horrible going through the motions of their 2005 stint at the Point. This week saw something entirely new, something close to a re-birth. The idea had been to do a live rehearsal of new songs intended for their next album. During the new material they became something akin to a teenage garage band, with primal bursts of vocals, Peter Buck's jagged guitar, and the blistering drumming of Bill Rieflin.

There was of course the sweetener of old favourites, delivered with the kind of hunger some people had long thought vanished. It was all a bit heady, like going back in a time machine to the days when REM were relatively unknown and cool, as opposed to the post 'Losing My Religion' days when they became coveted by the masses instead of the blessed nerdy few.

But the greatest thing about all five gigs at the Olympia this week was the reassertion of first principles. REM set out to have a great time and to give the crowd one in return, and in the end it was like a glorious goodbye to the overblown and illusory values of stadium rock. REM proved that stadium rock, at least in artistic terms, should be consigned to the grave where it belongs, and that the whole idea of a live rehearsal is truer to the spirit of rock and roll than a bunch of guys standing underneath a giant glitter-ball in a muddy field full of 40,000 people.

For once it was good to see the lack of hackneyed trappings that have become part of the arena circuit. Things like the call response that appeals to everyone's inner rock and roll zombie. The "we love you Dublin/London/Madrid" that elicits the collective Pavlovian roar which could terrifyingly hint at the possible universal lack of parental affection felt by thousands of people crammed into Croke Park/Wembley/Bernabeu.

And the merciful absence of cigarette lighters and singed fingers.

But of course this is the real world, and even REM will again succumb to the merry-go-round of market forces of an album-tour; the album-tour that has typified rock and roll since the 1970s. But in the meantime we had a lesson in intimacy and energy in the Olympia. We saw the kind of honesty sorely lacking in all the empty promises of connection and love delivered from in front of a bank of television screens by the likes of Bono. The kind of nonsense you'd hear while you wondered where your left shoe had gotten to in the mosh-pit, and was that your unconscious best mate who had just been lofted by a sea of hands into the waiting arms of stage security?

Instead, Michael Stipe stumbled over new lyrics, missed his cues, fluffed a verse or two, and chatted amiably to the audience in between moments of absolute brilliance. It was a wonderful two-fingered salute to the giant glitter-balls and lemons of stadium rock, and a lesson in artistic integrity that could provide just the shot in the arm that REM need after the disappointment of their last album.

Maybe it's time for U2 to up the creative ante and perform in a portaloo. And maybe Kevin Thornton knew something special was coming.

No wonder he was smiling.