A fortnight ago in these pages John Nathan, the JC's theatre critic, advanced the cause of his profession in the face of a growing onslaught by inexperienced, and sometimes inarticulate, amateurs blogging or tweeting their opinions about the latest plays.
Indeed. Any sensible, discerning theatregoer will surely trust the considered verdict of a veteran of years spent watching productions of every conceivable kind rather than the twitterings of a tweeter or the blusterings of a blogger.
In particular, he asserted, dramatists, actors, directors and other theatre workers value the responses of the experts. Frequently honed by serious research, the conclusions of professional critics are, it seems, as the oil that turns the wheels of creativity. Theirs is practically an academic discipline. And John Nathan cited with approval Maureen Lipman's disdain for one reviewer who - tam vulgaris! - "writes like a fan".
I certainly agree with John that informed opinion should be infinitely more helpful and valuable than the opposite. And you would be justified in assuming that the opinion of the doyen of present-day theatre critics, the Guardian's Michael Billington, would probably be the most informed of all. A magisterial reviewer, Billington can boast of decades of experience - all of which he has drawn upon in compiling a list of what he declares to be the 101 Greatest Plays, just published by Faber.
His choices and rankings are completely personal and, along with the indisputable classics among his century-plus-one can be found several idiosyncratic indicators of Billington's individual taste. (I suspect his publishers will relish readers' challenges citing "glaring" omissions or "eccentric" inclusions.) Not even the most eminent critics agree with each other all of the time on the worth of all plays or productions. (Which, to me, shows - pace Maureen Lipman - that the greatest critics are also the greatest fans.)
Of course, in a very basic sense, the merits of any artistic creation boil down to personal opinion. If 99 per cent of reviewers, audiences, readers and scholars rate Three Sisters more highly than The Mousetrap, that doesn't make the majority view a scientific fact of the order of the statement that, when water is heated to 100 degrees centigrade, it will boil.
On the other hand, it doesn't take prolonged exposure to the dramatic canon to believe that the unique genius of one, particular playwright is all but such a scientific fact. And, with regard to that writer's works, the list drawn up by the man widely regarded as the country's leading theatre critic is… barmy.
Forget about the absence, from 101 Greatest Plays, of Waiting For Godot, not to mention Death of a Salesman (which Billington doesn't), it is the Guardian's man in the stalls' cock-eyed view of Shakespeare that has disastrously undermined John Nathan's case a mere matter of days after his making it.
Billington has found room in his 101 for only six of the Bard's works - the highest being Love's Labours Lost at number eight (Hamlet is rated 10th). Among the many left out are A Midsummer Night's Dream, The Tempest, Measure For Measure, and one of the most colossally powerful works of art in the history of civilisation - King Lear.
I recall, some years ago, attending a lecture in Israel by a prominent academic on the respective Jewishness of the work of three of Britain's leading playwrights, Harold Pinter, Peter Shaffer and Arnold Wesker.
Pretty straightforward you might think. Most Jewish: Wesker, obviously, author of a trilogy that begins with Chicken Soup With Barley, centred upon the highly charged Jewish family unit of Sarah and Harry Kahn and their children Ronnie and Ada in London's East End in the 1930s, and ends with I'm Talking About Jerusalem. Second most Jewish, though a long way behind: Pinter, the characters in whose play, The Homecoming, some argue, are "symbolically" Jewish, and who includes a character called Goldberg in The Birthday Party. Miles more behind, in third place: Shaffer, whose spectacular body of work, including Equus, The Royal Hunt of the Sun and Amadeus - none of which, incidentally, features in Billington's top 101- displays little or no trace of Jewishness.
But, no, our learned lecturer placed them in precisely the reverse order, postulating that Shaffer is the most Jewish and Wesker the least. Which goes to show that, while expertise is important, it is no guarantee against the preposterous.
After all, in John Nathan's thesis, the man whose opinion is likely, among all critics, to be of the greatest value to theatre practitioners, thinks Mike Bartlett's King Charles III is better than King Lear.
You couldn't tweet it!
To get more from Life, click here to sign up for our free Life newsletter.