Yet in its own sublimely silly, rulebook-tearing fashion, the National Theatre performance of Brent's Love Upon the Throne is a rapturous illustration of what he means. For as well as being the funniest show of the year, this piece has a curiously touching self-reflexive quality. Hapless inadequates thrust into roles they can't manage play, well, hapless inadequates thrust into roles they can't manage.
So it has a revelatory aspect, too; by highlighting the kinship between the predicaments of an actor and the predicament of a royal, Love Upon the Throne exposes the inherent sympathy in theatrical presentations of monarchy, even those designed to be satiric.
Meanwhile, a real eye- opener, or rather ear-opener for me was the intensity of the silence at both performances I attended of the National Theatre's production of Copenhagen, my play of the year.
Michael Frayn's profound and haunting meditation on science and morality and the ineffable mysteries of human motivation explores difficult material with a searchingness that simply would not be risked in a television play or film.
In some austere afterlife, a trio of people re-enacts the enigmatic visit made in 1941 by the German physicist, Werner Heisenberg, to his Danish counterpart and erstwhile mentor, Niels Bohr. This puzzle opens up matters of stupendous moment.
Some complained that it was a treatise rather than a play. But the essence of drama is rhythm and, as Michael Blakemore's production beautifully brought out, Copenhagen is built on the recurring rhythms of re-enactment. A dazzling achievement.
The past year has also stretched credulity, on the theatrical front, in several pleasing ways.
A Racine season in the West End? This seemed about as feasible as a Ray Cooney retrospective at the Bouffes du Nord, before the Almeida's Jonathan Kent triumphantly brought it off with Diana Rigg and Toby Stephens. Then again, a solo gig from David Hare? Surely they meant to book Jackie Mason?
But Via Dolorosa, his reflections on a first visit to the Middle East, was no mere what-I-did-in-the-holidays lecture with slides, nor a lazy substitute for a play.
A gripping dramatic monologue about the ambiguous benefits and penalties of faith, communicated with wit, fire and growing confidence, it managed like many of the best things this year - Sarah Kane's Crave, Mark Ravenhill's Handbag and the brilliantly baleful junk-opera Shockheaded Peter - to disturb your assumptions about what form a theatrical experience can take.