The dead leave their wisdom behind, but we never manage to grasp it

The story of Robert the Bruce's heart is about confidence that the past can be used as a weapon

They have dug up the Bruce's heart. A team of archaeologists working at Melrose Abbey has discovered a leaden casket. In it, they presume, is what's left of the cardiac muscle that powered the victor of Bannockburn. The diggers were really looking for the foundations of the Chapter House. But archaeology is so poverty stricken these days that any publicity helps.

A much earlier dig, in the 1920s, had already turned up this casket. It was reburied, unopened, and this is what the archaeologists will do this time once the Edinburgh laboratories have finished examining it. But I am not sure if that is the right approach. The story of the Bruce's heart is not about respect and discretion for what is dead and gone. It is about flamboyant confidence that the past can be used as a weapon, even as a projectile, and that history can be stopped in her tracks.

When Robert the Bruce died in 1329, his friend and lieutenant, Sir James Douglas, had the king's heart removed and set out with it on a warrior pilgrimage to Jerusalem. But on the way through Spain, Douglas got embroiled in a battle against a bigger Moorish force. Seeing that death was inevitable, he is supposed to have taken the casket from around his neck and flung it ahead of him, into the ranks of the enemy, shouting: "Go on, Brave Heart, I'll follow thee!"

He charged after the heart, and was cut down. Next day, Sir William Keith found the casket under a heap of Scottish and Moorish bodies and he brought it back to Melrose, where it was buried under the altar.

For me, this story is a parable about time and its uses. There are those, like Sir James Douglas, who talk to dead ancestors (or their hearts) as if they were alive, and use the past as a missile hurled into the face of an unwelcome future. The Franco and Salazar regimes in Spain and Portugal were like that. So, in some ways, was the De Valera period in Ireland. The British Labour Party was certainly very much like that until Tony Blair got hold of it and suggested that it was better to chat up Moors and prosper than to throw Brave Hearts at them and die.

At the Edinburgh Festival this year, I saw a good many Brave Hearts flung in ugly faces. In John McGrath's A Satire of the Four Estaites, inspired by Sir David Lindsay's 16th century masque, an assortment of figures personifying "Auld Scotia's" virtues lobbed their hearts into the ranks of the wicked Murdoch media and rushed to follow them. The old virtues were believable; their modern foes less so. The real enemies who can yet destroy this "New Scotland striving to be born" live not in London, or even Sydney, but round the corner, in Edinburgh and Glasgow. They do not own newspapers, but write narrow-minded letters to them.

But this Festival showed its audiences many other cunning strategies to deal with the passage of time. The grand Giacometti exhibition included the tall-spindly bronze figures for which he is famous. But there was also a period in which his figures suddenly began to shrink, dwindling to minute figurines only an inch or so high. This was during the Second World War, when Giacometti escaped from Nazi-occupied Paris and returned to his native Switzerland, and these dwarf sculptures, somehow threatening to vanish altogether, are eloquent with fear and vulnerability. Many a species under threat has grown smaller, in order to be less conspicuous and to survive by consuming fewer resources. When Giacometti came back to Paris, it is said that he carried the whole of his artistic output for the past two years in his pockets. But that jingling bagginess in his trousers was like a packet of bronze seeds, the germs of a figurative sculpture which was to influence all Europe and America in the post-war years. Giacometti, in short, found a way of smuggling the future into the present.

All the same, the Festival's main device with time is the commando raid into the past. Such raids see some unsuspecting work of art from a previous age and hoist over it the flag of the present. Drama at the Festival is still almost completely dominated by East European companies, and, in that part of the world, the bible for directors and dramaturges seems still to be Shakespeare, Our Contemporary, first published nearly 40 years ago by the Polish scholar Jan Kott.

It ought to be time for a critical revolt against this tradition. The trouble is that the productions are so dazzling that they simply blow protests away. You prepare to get tough. Who says that Shakespeare had an intuitive sense of Stalin's personality when he wrote Othello or of General Jaruzelski's when he wrote Hamlet or that Richard III is Eduard Shevardnadze, Zviad Gamsakhurdia and Tengis Kitovani rolled into one terrific Georgian personality? But then the play starts, and in a few moments you are blubbering that little Estonia is the only culture in the world which can capture the sweetness of Romeo and Juliet.

Or take the proposition that Hamlet is a play about Poland, which is clearly ridiculous. But say that again 20 minutes into a production by the Pantomime Theatre of Wroclaw and I will pay off your mortgage in zlotys. As for the Georgians, who find Coriolanus far more informative about Tbilisi politics than the newspapers, it is hopeless to challenge their confidence that Shakespeare is alive and writing in the Caucasus. They seem to have his address, even if we have lost it.

Younger people I knew crowded to two night shows: to the Russian clown Slava Polunin and to the Polish open-air production in the University Quadrangle. This was Carmen Funebre, a nightmare of what befalls and has always befallen the conquered. Masked giants on stilts cracked their whips, burning models of cottages rose into the darkness on balloons, blinding lights swung, a woman was abused, impaled bundles burst into flame. Everyone who knows of Bosnia knew what this meant. Here was one spectacle which needed to play no games with time.

At such moments of theatre the past swings very close to you, almost close enough to grab as it passes. Afterwards, on a Sunday morning, we went out of town and climbed to the top of Cairnpapple hill. From here, on a clear day, you can see both coasts of Scotland.

Cairnpapple is a sacred site. There are the stone-sockets of a henge monument, cairns, burial chambers from late Neolithic to late Iron Age. In the course of over 3,000 years of holiness, the place has been rebuilt again and again as unknown people changed their styles of reverence for unknown reasons. Were these changes, like the shift from collective tombs to important individual burials, caused by foreign invasion and even ethnic cleansing? Historians no longer think so, and prefer to imagine deep cultural change - even the adoption of a new language - within societies which basically stayed put.

Sitting on the top, the grass hissing in the summer wind, I grasped a few obvious things about the past which I had missed. Nobody wants to be forgotten. The farmers and shamans of Cairnpapple did not put up stones in order to become an enigma to us. They did so because they wanted to transmit something to us, into that period which we call the future and which they perhaps conceived as a static zone called "Forever and ever."

So, mystery is no more than the failure of the dead to communicate. But they never stop trying. At Cairnpapple the dead are flinging the past forward in time at us, like Bruce's heart. But it always lands just out of reach. Out of our reach, but also out of theirs. For like Sir James Douglas, they must die in the attempt to break through time.