As Scotland has debated the politics of independence ahead of September's referendum, there have been related skirmishes in the cultural life of the nation.

How should the arts relate to this historic moment in our national politics? Indeed, should artists, arts companies and festival directors feel compelled to create works and shape programmes directly to the subject?

My opinion, for what it's worth, is that those engaged in creating and presenting works of art should be at liberty to approach, or not to approach, the plebiscite and the multitude of related subjects (political, historical and cultural) as they see fit. That is not a universally held view, as the criticism of Edinburgh International Festival director Jonathan Mills's indy-free farewell programme attests.

There is, however, one company which was never likely to even consider the option of side-stepping the referendum, and that company is the National Theatre of Scotland. The clue is in the name. A national theatre, by definition, is expected to find creative and original ways to reflect the nation back to itself; not least in periods of great national debate, such as now. As the Royal Lyceum's recent, misfiring production of Tim Barrow's disappointing play Union indicates, there are dangers in a direct theatrical address to a political subject. In Dear Scotland, the NTS has found a canny and innovative solution.

Comprised of 20 short pieces, by 20 writers, inspired by 20 depictions (in paint, photograph and sculpture) in the Scottish National Portrait Gallery, it spreads the burden of expectation (and the possibility of condemnation); much as Home, the NTS's inaugural productions (10 distinct pieces, by 10 directors, played almost simultaneously in 10 locations), did back in 2006.

As, in two 75-minute pieces, we are taken in promenade around, surely, one of Scotland's most splendid public buildings, we encounter monologues (such as Peter Arnott's splendidly satirical Sir Walter Scott and Liz Lochhead's poetically polemical Robert Burns) which address the referendum head on; others (like Stuart Hepburn's witty Chic Murray) which do so fleetingly, in passing; and yet others (Jo Clifford's thoughtful and affecting voice for an unnamed, literally faceless woman from Alexander Moffat's famously masculine painting Poets' Pub) which address other matters in our national life.

It is inherent in the nature of such a production that some pieces will be better than others. However, one soon forgives the less engaging sketches as one moves swiftly on to encounter Ken Currie's remarkable painting Three Oncologists, the recorded voice of dancer/choreographer Michael Clark or, a particular pleasure, an intimate encounter on a stairwell landing with one of our finest actresses, Maureen Beattie.

Ranging from Mary Stuart (aka Mary, Queen of Scots) and Elizabeth Windsor (aka HRH The Queen) to firebrand trade union leaders Mick McGahey and Jimmy Reid, Dear Scotland imagines a wonderfully diverse series of letters from Scotland's past to its present and future. It is, quite simply, an excellent idea, beautifully realised.