It probably should not have been a surprise to come across a commemorative medal, one dedicated to the courage of the New York police officers and firefighters of 11 September ("Buy 3 - SAVE $20 - $99.85"), lurking in SkyMall magazine, issued by United Airlines. After all, these days the medal is seen as falling into much the same "not quite sure what to do with" category as the Moonshadow Fountain or the Museum of Modern Art "perpetual calendar", or most of the other delights in SkyMall. This sort of medal now seems distinctly anachronistic - oddly, given that, after its invention in Renaissance Italy, it was a mainstay of collections for roughly four centuries.
But perhaps it is odder how little thought any of us is giving to how the memory of 11 September is to be transmitted, or how the events will be viewed in future - let alone rendered tangible and visible. We all seem pretty certain that "no one will ever forget", but we don't think about what will be remembered. Not even the most ardent propagandists appear to be worried about directing the memories of the future, at creating a history, rather than merely a present.
It wasn't always like this. The SkyMall medals represent the tail end of a tradition of representation and memory that was pioneered in a place and a period when eyes were turned not just to the past and the present, but very definitely to posterity. During the Renaissance, a whole category of object was specially invented - the commemorative portrait medal - to preserve the names and reputations of an elite, and to ensure that they would be remembered in certain ways. Their fascination now is in trying to disentangle fact from fiction. All that the great and the good of Renaissance Italy considered best about themselves is now on display at the British Museum in "Reflections of Glory: the medallic art of 16th-century Italy", an exhibition curated by Philip Attwood. Here is a whole gallery of reputations. These works of art may be unfashionably small, but they raise big questions.
Renaissance Italians invented the medal by looking at medaglie, two-sided ancient Roman coins, which they collected as part of their studies of a glorious past. For the men and women of the Renaissance, these coins were the empirical "facts of history". How quickly they realised that their own facts could be distorted. These are portraits of men (and women) who wanted to be remembered as new Hadrians. If they could not always achieve these ambitions in real life, they certainly weren't going to let history know.
They chose some of the best artists of their day - Benvenuto Cellini, for example - to make them noble, beautiful, heroic. What did it matter if they did not match up in real life? Men wanted to be remembered as fierce warriors and great peacemakers (not always contradictory), as pious, wealthy and wise. Women, on the other hand, were only expected (by the men who portrayed them) to be beautiful, chaste and modest. The great advantage of this particular medium was that it could deliver several complementary messages in a single package. Their reverse images - allegories of fame or fortune, depictions of battles or buildings, Dianas, Apollos and the wonderful Ganymede on a medal of Pope Paul III - expanded the meaning of the portraits. On both sides are explanatory inscriptions, identifying the portrait and telling the viewer how the whole thing should be interpreted.
This exhibition has portraits of Michelangelo and Titian, Philip II of Spain, a panoply of popes and a whole medallic biography of Grand Duke Cosimo de' Medici. But it also contains the carefully constructed memories of people who are utterly unknown. These, perhaps, are the pieces that demonstrate the commemorative function of the medal best of all, objects that are curiously touching for reason of their subjects' anonymity, but which, because we are remembering the unmemorable, are skewing history.
There is a portrait, for example, of one Antonio Bossi. Like so many of his contemporaries, he is bearded and serious; and on the back is Fame with her trumpet, and the words "I never die". Because of this piece, he was right. And then there is the question of honesty.
The star of this show is unquestionably a gold medal of Mary Tudor. It was exquisitely modelled, cast and chased by the Milanese goldsmith Jacopo da Trezzo at the time of the queen's marriage. Bloody Mary is now remembered chiefly for her propensity for burning Protestants. But there is something seductive about the quality of this piece - a beauty that tempts one to believe the rather flattering account of her features and even the unlikely message on the reverse. Mary is shown as a peacemaker - extending branches of palm and olive over a little bunch of suffering suppliants. It is not that one does not know any different: it's just that the image has an authority missing from most political imagery now. Perhaps there's a lesson there for Dubbya after all.
"Reflections of Glory: the medallic art of 16th-century Italy" is at the British Museum, London WC1 (020 7323 8000), until 22 September