This was the second time the film had been aired on Russian television in eight days, and both times, no matter the changed circumstances, the intent was the same: consolation and reconciliation.

Some countries, notably Russia and the United States, can all too easily cite examples of great movies that have served a rather different end – mythology – and left the nations that produced them noticeably poorer for the effort. Perhaps Poland’s experience of national self-improvement through cinema represents an example we and everyone can learn from.

Lenin’s hoary dictum on the critical importance of cinema was never better realised than by two 1927 films, Sergei Eisenstein’s October (10 Days That Shook the World) and Vsevolod Pudovkin’s The End of St Petersburg, both auteur classics whose images immeasurably aided the creation of a Soviet mythology from which millions of Russians are still recovering – and from which millions never will. In masterfully crafting a simple, visually indelible, good-versus-bad foundation narrative for the ignoble state that commissioned them, these films will forever provide refuge to minds too untroubled by the historical record to make distinctions great or small about what really happened in 1917 and beyond.

And why should they? They've seen the movie.

As seed-sowing propaganda, however, the Eisenstein and Pudovkin examples have to compete with DW Griffith's insidious The Birth of a Nation (1915), a film whose “unparalleled innovation and audacity” renders it for some “the single most important film ever made”, no less. Griffith’s simplistic, white supremacist recreation of the American Civil War and Reconstruction periods ignited anti-black riots in Boston, Philadelphia and other major cities, and the film’s unprecedented box-office success doubtless set race relations in America back by decades.

Without Griffith, of course, there could be no Gone With the Wind. Widely considered one of the greatest films of all time, GWTW is a successor story-of-the-offended-South which since 1939 has propagated both genteel myths and flagrant racial stereotypes as it subtly and overtly distorts American history for dramatic ends. It is hardly a stretch to assume that if this film had not been made – or rather, if it had not been made this way – Americans might have been spared much of the divisive agony of the nation’s civil rights struggle.

The disuniting, polity-corrosive effects of all four of these unarguably great films have been partially mitigated by movies of lesser stature, of course. Commendable post-Soviet films have illustrated the pernicious and divisive evil of Stalinism (Burnt by the Sun); the sad realities of Red Army mismanagement and criminal negligence during World War II (Punishment Battalion); the ambiguity of clergy and populace under German occupation (The Priest); and so on. Americans have likewise seen far more realistic portrayals of the minorities long ignored or abused in the self-comforting national “melting pot” narrative in To Kill a Mockingbird , Roots , Dances with Wolves and many others – all of them good movies, like their Russian counterparts here, but none of them an epic of “game-changing significance”.

For a contribution on that level, you have to look at Poland, and Andrzej Wajda's Katyn. This is not a good movie but a great one, and in no small part because it does not make a single nation better, but two.

Wajda’s filmmaking life and family history rendered him uniquely qualified to address the Katyn massacre – Poland’s great, aching loss of the last century, a wound to the nation’s heart rendered doubly painful by the five-decades-long, outside-enforced pretence that it was not there.

The national narrative that runs through Kanal (1956), Ashes and Diamonds (1958), Man of Marble (1977) and Man of Iron (1981) essentially made Wajda the guardian of the nation’s popular perception of its recent past. And as fate would have it, the country’s principal film chronicler had both a direct connection to the literally unspeakable tragedy still to be broached after 1989 – Wajda’s father was among those murdered by the NKVD at Katyn – and a strong and enduring cultural affinity to the nation responsible for the still-unexplained slaughter: Wajda loved and loves things Russian.

Briefly put, this director had the talent, authority, experience and personal stake necessary to make this film; and was also obliged, by nature and disposition, to make it as an anti-totalitarian rather than an anti-Russian story – an did just that. Thus Katyn emerged on three levels at once – as art of both sympathy and empathy; as art that returns a nation its history; and, thanks to the first two, as art that spreads that history as well.

If Katyn had not been made – or rather, if it had not been made the way it was, depicting two nations with compassion but also without flinching – no national screenings on Russian television would have been possible; no indelible images of what happened to the Poles, made palpable as individuals, would finally have been communicated to a Russian audience; and no meeting of Vladimir Putin and Donald Tusk – joined by Wajda himself, naturally – would have taken place at the Katyn site, marking a new level of mutual national understanding. Now that, pace Lenin, is cinema that really does approach “the most important of all the arts”.

Russian and US producers and directors should take note – and notes. Wajda’s unique suitability for Katyn should not render the gifted and farsighted of two great film cultures less audacious. Who will make a true and healing version of The Alamo or The Tragedy of Iraq? Can a 1917 that is both compelling and factual ever be filmed – or an Uprising in Budapest, or a Prague Spring?

History isn’t neat; it’s messy, often ugly and yields unwillingly to artists. Every nation needs to find its Wajda.