The words ‘10th Anniversary Revival’ are given as much prominence as the author’s name – Tim Crouch – on the National Theatre’s promotional material for An Oak Tree; a new ‘10th anniversary edition’ of the playtext accompanies. Such subtitling flags up its rare status: a genuinely experimental, fringe show that has achieved international acclaim, academic recognition, and much love from audiences – and performers (a key point, of which more later).

It’s not that often that shows based on a piece of conceptual art – Michael Craig Martin’s work of the same name which ‘changes’ a glass of water into an oak tree – and that originally opened on the Edinburgh fringe, get trumpeted ‘anniversary revivals’ at the National (even in the deliberately more restless Temporary Theatre space).

Before unpacking why An Oak Tree is – in many ways – an exceptional and era-defining piece of theatre that here makes a welcome return, I want to think about revivals more broadly: what the term can mean, the function and positioning of revivals in our current theatrical landscape, and how they shape our understanding of the past.

There are some shows we don’t even confer that status on – Shakespeare, most obviously. Others are done so often that they barely feel they deserve the term either: that Hay Fever or The Importance of Being Earnest are both on in the West End hardly feels worth remarking on, while it seems rare to go more than a few months without being told you must check out another Chekhov.

Other, more modern fare becomes canonised by starry revivals: texts like David Hare’s Skylight, Tom Stoppard’s Arcadia, Harold Pinter’s Betrayal become ‘must-sees’, ‘hot-tickets’. And when an anniversary comes along – afternoon, Terence Rattigan; o hai Arthur Miller – you suddenly can’t move for a playwright’s work, masterpieces and mediocrities alike.

All of which can mean a chance to see sparkling, arresting new takes on some of the greatest works ever written. Or they can be rather yawnsome. Rehashing well-known works risks feeling like safe cashing in for theatres and producers, and checking out for audiences, comfy in the knowledge these are ‘great plays’ – tick – with coo-worthy casting – tick – that you already vaguely know the plot to – tick. They clean up at awards seasons too.

Of course we all crave simply glorious entertainment or reliably well-crafted artworks at times; I’m obviously not saying throw these plays in the dustbin or only stage new works. But a lazy revival can be a deadening, ungalvanising experience.

Talking to young director Robert Icke recently, he was typically blunt on the matter: “in the etymology of revivals, it’s about bringing the plays “back to life”. A lot of the time when you see revivals, that has failed.”

And yet he’s staging a very old play this season: Aeschylus’ Oresteia at The Almeida. Yes, he’s written a new translation, but the challenge is still to take breathe life into an ancient text (his plain-speaking, modern production succeeds with admirable ballsiness and totality of vision to my mind).

But while discussing the basic question – ‘why do the Greeks?’ – he raised an interesting point regarding revivals: some truly classic plays just don’t get done very often. “I think I know my Greeks – but actually, when have I had the chance to encounter these plays? You are giving a whole generation a chance to see these big important things they’ve [only] read.”

It’s striking that there are not one but three versions of The Oresteia this year – and all by young directors/writers, with Rory Mullarkey tackling it at the Globe, and Blanche McIntyre directing at HOME in Manchester. Perhaps this does reflect that fact that there’s a generation who have only really read it – and heard about great, seminal productions of the past.

Theatre history calcifies around a few key game-changing productions – and Peter Hall’s masked Greeks for the National Theatre are undoubtedly amongst the most legendary. But this means the underlying plays can take on strange half-lives. Younger theatre-makers know certain texts are Very Important, but they don’t know how they theatrically come-to-life; reading is not theatre, after all. And plays that are already considered to have had a ‘definitive’ production or ‘seminal’ interpretation can be fearsome for young practitioners to approach; there are long shadows across the pages of certain scripts.

Meanwhile works that were huge new-writing successes in their time don’t necessarily enjoy a busy afterlife, except in reputation. There is, therefore, something to be said for putting them back on their feet – and appetite for it too: I couldn’t have been more excited about seeing Peter Barnes’ The Ruling Class, having been introduced to it by an enlightened school teacher, and yet observing that it’ just never done. Recent revivals of Shelagh Delaney’s a Taste of Honey and David Storey’s Home were also a treat – texts taught at university yet gracing stages surprisingly infrequently.

The same goes for edgier modern classics. The chance to see shows that are infamous for causing a scandal is, today, rather instructive: was the stoning the only interesting thing about Edward Bond’s Saved? (No.) Does Sarah Kane’s Blasted still have the power to shock? (Yes.)

Which leaves one in a tricky situation when assessing the wisdom of some programming. Take Trevor Nunn’s decision to revisit The Wars of the Roses next year – Peter Hall and John Barton’s condensed, if still epic, cycle of Shakespeare Histories staged by the RSC in 1963 is seen as a major milestone in British theatre history. On the one hand, this is surely a backwards-looking resuscitation; on the other, I can’t help that I wasn’t alive for the original, and I’d quite like to see what all the fuss was about.

Excitement and innovation cannot be recaptured however – so do you value such revivals as a merely historical works, interesting to theatre-nerds and the nostalgic? Or do the truly greatest plays transcend their famous moment, saying something new each time they’re revisited by fresh and hungry eyes?

Returning to our 10th anniversary revival: An Oak Tree provides an inventive (if one-off) solution, that nonetheless also helps remind us what theatre is, what it can be. This may be an anniversary, but there’s no risk of it harking back to a ‘definitive’ production: every show has been different, for a different actor plays a main part every time. What’s more, that actor has never seen the script: they are fed every line live, through headphones, sight-read off scripts or baldly through being told by Crouch what to say: “Say ‘I’m Andrew Smith’”.

The audience knows this, and we become potently aware of the liveness of theatre: it makes doubly real the old cliché that no two performances are ever the same. By highlighting the underlying processes of acting – being given lines; emoting on cue – the show points out the fakeness of performance. Yet, by being an elaborately constructed, precisely-followed text, even with scripted, meta-theatrical between-scene ‘chat’ between Crouch and the actor, it has a heightened theatricality; it reminds us that all theatre is an absurd, magical act of belief.

And if all that sounds a bit theoretical, the real brilliance is that the story – about a stage hypnotist and a grieving father, about the power of transformation – is also moving. It’s as if by pointing out the artifice of theatre convention, Crouch frees us from it. We go with the story wholly, even as it’s reminding us it cannot possibly be ‘real’, that we are participating in our own imaginative act of transformation. It’s a rare example of form and content dovetailing beautifully.

As such, An Oak Tree has become one of those seminal works I was talking about, for a new generation. Certainly, seeing it in its first Edinburgh run, it had a huge impression on me. It rapidly made it onto my syllabus at university, and Crouch’s new works became must-see for our cohort of young, lively-minded students, as well attracting more weighty academic dissection. Crouch’s plays have since been performed all over the world, with An Oak Tree enjoying numerous tours in the decade since its premiere; his work’s influence can surely be seen in the metatheatrical and playfully self-aware work of young companies in the UK today.

But for all that, this isn’t really a 10th anniversary revival: a reheating of a play now given legendary status. For An Oak Tree demands to be made afresh every time a new, unknowing actor walks onstage – and every time a new audience knows that, and ripples with anticipation for how the show might unfold. Now all we’ve got to do is work out how to give every revival of a much-loved classic such a shot in the arm…

An Oak Tree is at the National Theatre till 15 Jul, and at the Traverse, Edinburgh, 9 to 16 Aug