With From Russia, the Royal Academy's new exhibition, we have witnessed not only the now customary hyperbolic claims of the biggest, the best, the first and most extraordinary that sane men have learned to disregard, but international political involvement serious enough to bring light into the eye of the most jaundiced conspiracy theorist.
This exhibition has for three years been in the planning and preparation stages; sponsored by a German power company, it has without a whisper of a problem been on show in Dusseldorf since 15 September last year, yet on 19 December the Russian authorities cancelled its transfer to the Academy, fearing that the some 120 paintings lent by four Russian state museums might not be "immune from third-party confiscation".
The weeping and wailing could be heard as far away as Timbuktoo. The greatest exhibition that the world has ever seen could not take place and the Exhibitions Secretary of the Academy claimed that this great institution would be financially ruined; others opined that this cancellation marked a return to the Cold War, was a response to the Litvinenko affair, and that art was again reduced to a pawn in the game that great powers constantly play, the demand for immunity from third-party confiscation the first of many moves that might lead to political checkmate.
To counter this, the former Culture Secretary, James Purnell, brought into play not a pawn, nor knight, nor bishop, but his queen, the most powerful of all his pieces, Parliament itself, and surrendered her. There was no calling of bluff nor even playing the game for a move or two, just abject surrender.
While all Westminster was away pulling crackers and donning party hats, James Purnell, unhindered by debate, tinkered with the act that protects cultural objects borrowed from abroad and enacted a law that grants untrammelled "immunity from seizure" to all foreign artistic property on temporary display in Britain. At this, Timbuktoo heard the echoes of great rejoicing in Piccadilly and the mantra of the biggest and the best began again, boosted by the fact that Parliament, our great instrument of democracy, justice and fair play, had intervened to secure for our delight the most significant exhibition ever mounted in this country.
To me, however, it has seemed a wretched business. I am appalled that when the Russians snapped their fingers and demanded an amendment to the act, Purnell complied. No minister in a British government of any political complexion should ever, for any reason - and certainly not over a domestic commercial issue as trivial as an exhibition of pictures - capitulate to the wishes of a foreign state.
Purnell, either badly advised by civil servants, steered to their advantage by the honey-tongued knights of the Academy, or merely driven by adolescent and ignorant enthusiasm for the field to which he has so recently been appointed, looked no further-than the end of his nose and did not see that not only has he dented British sovereignty, but that his new law may well frustrate legitimate claims to ownership by descendants of those to whom these pictures belonged when the Russian state chose to expropriate them.
I see no moral distinction between the loss of property by private citizens as a consequence of the Russian Revolution and the Nazi regime in Germany. If, anywhere in the world, there are descendants who can prove themselves to be the heirs of the Russians who, early in the 20th century, were among the most formidable collectors of their day, it is not the business of a British government to frustrate any claim they may choose to make. Purnell's new law is doubly disgraceful, doubly shameful, and puts Britain on the side of the looters.
To this, many will respond with Jesuitical fervour that the end justifies the means, and The Guardian has set the tone with its claim that the prize exhibit, La Danse, by Matisse, is "the most beautiful modern painting in the world ... the most glorious work of art that we will see this year". It is a picture with a mythical reputation. Commissioned in 1909 by Sergei Shchukin, a Russian textile merchant who was the Saatchi of his day in the number of his purchases and the insecurity of his judgment, it was briefly exhibited in Paris on completion in 1910 and was then sent to Moscow.
After the Revolution, it was transferred to the Hermitage in Leningrad; there the Stalinist authorities, as vigilant as the Nazis against what they deemed decadent art, came within an ace of destroying it. To all intents and purposes it disappeared, and when, in my young day, tutors at the Courtauld Institute spoke of it, they did so with breath bated, so in awe were they of a work that none had ever seen.
La Danse is now a classic example of knowledge so repeatedly received and reinforced that it cannot be challenged, and with the recent propaganda campaigns of art historians determined to reduce the reputation of Picasso in favour of Matisse as the great genius of the 20th century, it has been established as "the most beautiful modern painting in the world".
Most beautiful? Not for those who, like me, believe that ugliness can have a dimension far more beautiful than beauty and, without a moment's hesitation, can count a dozen paintings by Picasso that better deserve that accolade, one of them the grotesque Dryad of 1908 that Shchukin also owned.
La Danse is as flaccid and ill-drawn as it is big, the composition cramped by the canvas edge, the coarse brown outlines of the misshapen and distorted figures crude, the colour (so much over-praised) mere filling without modelling, thin paint scrubbed into the canvas, the surface dull and dry. That Matisse's handling of paint could be rich is demonstrated by The Red Room painted two years earlier - a disastrously but deliberately decorative picture, its triviality heightened by the presence of Picasso's Dryad. This primordial woman, awkward on her hind legs, just risen from all fours, is Cubism at its purest, simplest, freshest, most exhilarating and approachable manifestation, the clumsy first experiments resolved, the false logic of later aspects of Cubism still years away.
She is the colour of raw timber from the tree of which she is the nymph and as roughhewn as a totem; light falls harshly on those planes that are at an angle to reflect it - shoulder, thigh, thrusting belly and sagging breast - the soft curves of flesh boxed in cubes and cones and pyramids. It is an ugly picture, deeply beautiful.
Roughly half the exhibition is devoted to French paintings, a handful of late 19th-century Salon pictures and then a quick scamper from Impressionism to Cubism; the other half is of Russian paintings that reach a little further into the 20th century. Neither particularly illuminates the other, though any fool can point to parallels, and but for a dozen or so exceptions, neither group is particularly distinguished - the French things are of a quality still to be found in the sales of Christie's and Sotheby's, and too many Russian things are of the dull and derivative provincial quality that one might expect of museums on the further reaches of the Trans-Siberian Railway, rather than in St Petersburg or Moscow.
The sane man wonders at the dreary and conventional choice - were these thrust on the Exhibitions Secretary or did he pick them from an Argos catalogue? If this is the great Norman Rosenthal's swan-song, then he would have been wiser to stay mute.
Why? - is the only reasonable response to the Rousseau, the Corot and a Daubigny that the National Gallery would hardly bother to display, to the Christie Monets, the Sotheby Pissarro, the commonplace Cézannes and a back passage Braque, all of a type far too familiar. Why choose such ordinary things by Besnard, Denis, Bonnard, Vuillard and Van Dongen? Is this the moment to introduce a British public to such unimportant bores as Guérin, Vallotton and Marquet?
Even the Gauguins seem off-song, and Renoir's Portrait of Jeanne Samary has so strong a claim to be the worst depiction of an actress ever painted (thigh deep in what appears to be a collapsing wedding cake) that the sane man is willing to pay good money not to see it. Two paintings stand out amid this dross - The Blessing by the forgotten Pascal Dagnan-Bouveret, an exquisite study of light on white, direct, diffused and reflected, and James Tissot's Ruins, a key work in his late reinvention of himself as a profoundly Catholic painter. Among more adventurous things, two landscapes by the underrated Derain are quite marvellous.
Of the Russian paintings, too many are familiar from recent exhibitions at the National Gallery, the Barbican, Tate Modern - where Kandinsky's thrilling Composition VII was on view for months in the high summer of 2006 - and even at the Academy itself which gave us Chagall's Promenade less than a decade ago. The impression given by the French paintings that Russia operates a very limited bank of travelling pictures from which borrowings must be made is heavily reinforced by so many old acquaintances among her native artists.
I had hoped that Ilya Repin, great history painter, might be represented by a dramatic masterpiece rather than the less important October 17, 1905 that the Academy idiotically hangs above a door rather than low, as its viewpoint dictates; hoped too that in the works of others in the group known as The Itinerants we might have seen much more of their startling realism - but no, and instead we scamper into second-hand-post-Impressionist adventures and the hopeful notes of Tatlin and Malevich, again almost too familiar.
Far from the superb visual challenge, the revelation and the eye-opener announced in this very newspaper last Tuesday by a hapless scribbler rushing to join the judgment dictated by the Royal Academy, this exhibition is a depressing disappointment; all who go to it will be the victims of the ignorance and confusion of those who mounted it and the Academy's always cynical management of propaganda.
It is a poor reward for a Culture Secretary's moral turpitude. The Russian Revolution was ultimately a great and continuing crime against humanity, the cause of far more deaths than the Holocaust with which its consequences overlapped and to the victims of which we make strenuous efforts to return expropriated property. James Purnell's law against the heirs of the Revolution's victims rescued the Academy from financial loss in the failure of a strictly commercial enterprise of no educational value but it was a squalid and spiteful little measure unworthy of a statesman, unworthy of us all, and we are sullied by it. All with a sense of decency should boycott this exhibition.
• From Russia is at the Royal Academy (020 7300 8000) until 18 April. Daily 10am-6pm (Friday until 10pm). Admission £11, concs available. www.royalacademy.org.uk