I have only one serious complaint about the RSC's eight-play Shakespeare history cycle: it hasn't been seen nearly often enough. Only twice in April was it possible to view the plays in strict chronological sequence. Contrast that with 1964, when Peter Hall staged a similar cycle at Stratford. Admittedly, the Henry VI trilogy was condensed into two plays under the generic title of The Wars of the Roses. But the seven-play cycle, from Richard II to Richard III, was performed countless times through a Stratford summer. What was then a popular success has become a collector's item.

But mention of 1964 shows how the histories constantly shift their meaning. Two key influences dominated Hall's version: Bertolt Brecht and the pioneering Polish critic Jan Kott. What emerged was a vision of Plantagenet England as an endless treadmill of violence: in the words of the New Statesman's Ronald Bryden, "a lightless tunnel of historical error down which leaders and commons trudged deathward through mounting pain and obscenity, pulling their small victualling wagons".

The anti-heroism of the 1960s still pervades the latest cycle. But the effect is surprisingly different. Hall and his co-directors gave the plays a deliberate continuity, as if we were watching the enactment of a curse. Today the plays are called This England, and the sense is of fragmentation, as if to mirror our current national divisions. Four directors tackle the eight plays in radically diverse styles, and they are staged in a range of venues, from the Barbican to the Young Vic. And England is symbolised in differing ways: a mound of earth, the flag of Saint George and jingoistic hymns in Steven Pimlott's Richard II; a curving wall of steel in Michael Boyd's Henry VI trilogy. The shifting perspectives echo the central idea: that any cohesive sense of national identity has been lost and is only briefly, and horrifically, resurrected through a foreign war.

Shakespeare himself is now under attack today. Does he have anything to say in a hi-tech, multicultural, globally capitalist world? When you see the plays performed, the questions become literally academic. In particular, the so-called "history cycle" is grossly misnamed. In reality, it is an eight-play political cycle that constantly returns to key issues of the corrupting isolation of power, the difficulty of combining justice and liberty, and the danger of division spreading through a factionalised land. But these ideas are not abstractly debated. The genius of Shakespeare is that he explores through drama the daily process of politics.

Though nominally about England, the plays have international application. Anthony Sampson recently nailed the absurdity of the ANC's proposed proscription of the pessimistic tragedies by pointing out the dependence of Nelson Mandela and his fellow Robben Island prisoners on their own heavily annotated copy of Shakespeare. But, shortly after reading last week of the internal plotting against the South African president, Thabo Mbeki, I found myself watching a precise replication of the process on stage in Henry VI Part Two. It is exactly the means by which the English nobles get rid of the all-powerful Lord Protector.

You'd be hard-pressed to find any country where the plays' analysis of power, justice and the fragile tension between order and chaos is not immediately relevant. But there is a danger in always justifying Shakespeare by his prophetic insight into current events, as if he were some kind of theatrical Nostradamus. Followed closely by Schiller, he was the best of political dramatists because he understood the mechanism of power. What I also took away from the RSC cycle was a heightened awareness of Shakespeare's moral ambivalence: his uncanny ability to see both private character and public events from every perspective.

Shakespeare's private obsessions also emerge when you see the plays in bulk. People often say we know little of Shakespeare. I'm always astonished at how much we do actually learn about him from the plays. On a trivial level, I've never noticed anyone comment on his fixation on body odour and halitosis. More seriously, sequential exposure to the histories reveals a preoccupation with fathers and sons. Was it because his own son, Hamnet, died at the age of 11? Whatever the reason, Shakespeare's obsession permeates these plays - a point brilliantly grasped by Michael Boyd, who, in the second tetralogy, casts Keith Bartlett and Sam Troughton as a succession of fathers and sons. Nothing in the whole cycle is more moving than the soldierly Talbot's belief, as he cradles his dead son in Henry VI Part One, that the two of them will somehow cheat tyrannical death by being "coupled in bonds of perpetuity".

But what you also get from seeing the plays together is a sharpened sense of the polyphonic variety of Shakespeare's language. At a lively public debate about the histories last week at the Barbican's Pit, Maureen Duffy ended the session with the observation that Shakespeare is "our linguistic rainforest". It's a dazzling aphorism, implying both multifarious variety and imminent decimation. And Duffy earlier argued that, because English risks dilution through being adopted as the language of commerce and travel, we need more than ever to hold on to the democratic abundance of Shakespearean speech.

And if any moral emerges from the RSC's big idea of staging all the histories, it is that Shakespeare should not be viewed as an elitist hobby for the lucky few but as a source of political understanding and linguistic empowerment. Even at this late date, is it too much to hope that this cycle can somehow be preserved on television?

• Henry VI and Richard III continue at the Young Vic, London SE1 (020-7928 6363), until May 26.