If all the Fringe is a play, then Edinburgh is a stage set par excellence. Robert Louis Stevenson's "dream of masonry and rock" is as beguiling and romantic a backdrop you could hope to find, and the fact that theatre is seemingly blooming out of every crevice in that masonry only adds to the appeal of what is arguably the greatest show on earth. And if the scenography is courtesy of Auld Reekie itself, the metteur en scène must be the rain: a pluvial Prime Mover, which changes the scene from the sublime to the soggy, and directs and controls the flow of people in the city - we coalesce, we disperse. The fug and steam of the cooling cagoule fill the auditoria. And just as well something is, because the average audience size on the Fringe is just nine.
At two and a half thousand, the number of shows this year is nearly a fifth up on 2009. But unless punters multiply by the same logarithm, your average audience size is only going one way. Not helped by a theatrical Darwinism, where the super-venues get bigger and fatter at the expense of the one-woman-and-her-overdraft sound of one hand clapping majority.
Then there's the vexed issue of the household names, the so-called "parachutists", one of whom even parachuted into an improvised musical I was rather enjoying. Nicholas Parsons is urbanity itself, but his presence at Showstopper! was just that. (That said, the company created some delectable moments out of his chat - the Rocky Horror Show version of his two marriages rather sticks in the mind). The crump of celebs jumping on the bandwagon could be heard right across the city: Alan Cumming, who has conveniently come over all Caledonian, seemed to be on the cover of every local rag. " I have never felt more Scottish!" he whinnies. This, despite living in America, and taking US citizenship.
However, the deep-keeled Fringe is something of a self-righting machine: as soon as the organism senses it's too mainstream, it germinates Fringe fringes: Forest Fringe, Free Fringe, and this year, The Living Room. And there are a huge number of performers for whom a stage is a bourgeois luxury: a loo, or the back of a van will do. If you want the up and coming, and not the been and gone and got the TV show, these are your hunting grounds.
But the pursuit of this ignis fatuus can be wearying. Where to start? Iranian poetry or Russian clowns? On one production-laden afternoon, the very names of shows and companies seemed to forge a queasy objective correlative: Ad Infinitum, then The Dreadfuls, rounded off by Beautiful Burnout. It can seem like the craic is just elsewhere: it's in the nature of Edinburgh's pop-up venues that you can often hear what's going on around you, and during the Emma Thompson-endorsed Fair Trade I could hear Flawless, Chasing The Dream and their West End transfer. Other people, I fretted, were having more fun.
Every year a political anxiety flares and spreads, like a chant in a football stadium, across Edinburgh's productions. A few years ago it was Blair, but now sex trafficking is the issue that has sparked several shows and crossed into stand-up with Keith Farnam's How Much is that Woman in the Window? (How Tony might feel about being bracketed with sex trafficking as a societal ill can only be imagined). Fair Trade may have felt like dressed up agitprop, but there were other shows, lacking the imprimatur of an A-lister, which packed a greater punch: Roadkill, for example, bussed spectators to a tenement flat, and immersed them in the truly horrifying "business" of slave-rape.
2010 also saw the rise of the viral star: the performer who has achieved their rep and their access to the platforms of Edinburgh on the net. The brightest of these has to be scabrous teen joker Bo Burnham (60 million hits), but I followed my own star in the form of "You Tube Sensation" The Unexpected Items, on the strength of Gap Yah (2 million hits) who have a posh totty charm all their own. And the buzz about shows spreads like a contagion, too: blogs, tweets on the Fringe ("twinges") and the most reliable of these viral modes, word of mouth. My street tipster was right on the pulse with his recommendation Meow Meow: never mind the politics; it was cabaret and Glee Club escapism drawing the crowds.
I left Edinburgh as some Chinese acrobats were carefully preparing their own stage on Princes Street. A man dressed as a penguin wandered by. I reached the cover of Waverley as the heavens cracked open and the rain swept these visions away: another scene change in the greatest show on earth.