The tragedy of King Lear, with its naked, ranting king, was, explains historian and broadcaster Simon Schama, written to be performed in the presence of James I, who, like Lear, was famed for his need of flattery.
"Lear's weakness was also notoriously James's. There was no praise, however fawning, that wouldn't go down well with the king. No playwright, before or since has got under the skin of the nation like Shakespeare," says Schama, whose two-part BBC documentary on William Shakespeare begins this week.
It is this, he contends, plus his unparalleled ability to appeal to "gents and groundlings" alike that establishes Shakespeare as the keeper of our national identity. In fact, Schama goes further, crediting the Bard not just with characterising England and the English, but with creating the very idea of England.
"Shakespeare's audience could see England on the stage almost before it existed in reality," he says. "Shakespeare was born some 30 years after the Protestant Reformation began, divorcing England from Catholic Europe. For the first time, England was on its own, and the English needed to know who they were, what made them unique and what their story was. History was not just one of Shakespeare's great obsessions, it was the obsession of the age."
Religious schism also forged a new form of popular theatre. "Shakespeare's theatre could only be born once an older, Catholic theatre had been killed off," says Schama.
For a mainly illiterate audience, storytelling, pre-Reformation, had been largely visual - the populace received much of its religious education through spectacular paintings in churches. Medieval mystery plays and miracle plays were also full of spectacle. Protestantism, with its fundamentalist mistrust of "imagery" and strict reliance on "The Word" of scripture, demanded a new, but equally gripping art form.
"It is one of those miraculous historical coincidences that Shakespeare, a child with a genius for storytelling, should be born at a time when the Word became supreme," says Schama.
The "great word-picturer", he explains, effectively reshaped the way we speak. "In the second half of the 16th century, English was transformed. Hundreds of new words and phrases appeared in print every year and many of them appeared for the first time in Shakespeare's plays. More than likely, he didn't invent words and phrases such as 'foul-mouthed', 'puke', 'queasy', 'fob off', 'good riddance' - they were there in the mouths of the people."
"What Shakespeare did was to wire together the world of the high-ups and the world of the low-lifes. By doing that, he expanded what literary English was and out of that expansion came imagery rich in ideas - 'the green-eyed monster', 'spotless reputation', 'the world is my oyster'. And after this word revolution, we all think bigger and in brighter colour."
The revolution carried all before it. As Shakespeare was sharpening his quill, the first purpose-built playhouses in England since Roman times were packing in the punters: "In the 1550s, the great crowd-pleasers had been cockfighting and bear-baiting," says Schama. "But by the 1590s, between 15,000 and 20,000 Londoners saw a play every week."
What they found there - specifically, what Shakespeare gave them in his early history plays about the Plantagenets, the Yorkists and Lancastrians - was a new, nationalist consciousness. "It was a kind of communion of Englishness," says Schama. "What we feel at Wembley, they all felt at the Rose, the Curtain and the Globe."
Contemporary records suggest that one in 20 Londoners went to see Shakespeare's Henry VI on its first run. It is, by modern standards of theatre-going, an astonishing statistic, but Schama is impatient with suggestions that Shakespeare may have lost his common touch, that classical theatre today is more accessible to "gents" than to "groundlings".
"I think it's incredibly patronising of anybody to suppose that is true of Shakespeare. I was recently on the judging panel of Shakespeare by Heart. We were listening to children - all from state schools - who learned long speeches by Shakespeare. They weren't all white, they weren't all pink or beige - they were exactly the face of young Britain that you'd expect and had absolutely no problem with the language or meaning of the plays. They were utterly wonderful."
"Shakespeare isn't scary. It shouldn't be scary. And to suggest that schools, for example, shouldn't teach him or should teach him less because he's not 'accessible' is robbing children of an incredible experience with their own language and an understanding of what it means to be human."
Even when Shakespeare confronted the monarchs, he did so on a deeply personal level. When Hamlet was performed at court in 1603, the audience would have been acutely aware of the parallels he drew between Hamlet's circumstances and those of King James I.
"As the plot unfolded, James must have felt increasingly ill at ease," says Schama. "His father, Lord Darnley, had been murdered. The murderer, James Bothwell, had married James's mother, Mary Queen of Scots, and the pair lived as king and queen, flaunting their crime very much like Claudius and Gertrude in Hamlet. This was the nightmare that haunted James and here it was, being played out right in front of him."
From the rousing patriotism of Henry V to the sophisticated, political philosophy of Hamlet, Macbeth and King Lear, Shakespeare's view of royalty is deeply equivocal.
"On the one hand, Shakespeare's monarchs are living symbols of their country," points out Schama. "Yet his kings and queens are also shown as grandiose, bloody-minded, sociopathic. And the question Shakespeare asks them, more insistently, more tragically than anyone before or since, is: what happens when the human animal breaks through the mask of royalty?"
So how did Shakespeare manage to get away with it? "The sheer audacity is breathtaking," agrees Schama. "And this in an age when writing was a dangerous game. Of his contemporaries, Kit Marlowe was murdered, Thomas Kyd was tortured and Ben Jonson was thrown in gaol. Shakespeare must have thrived on the thrill of it."
"And, you know, he was a shifty b****r. He was trained in classical rhetoric, so he was able to present all sides of an issue. But he also had this amazing capacity to get under the skin of an incredible range of different types and ranks."
"It's partly, I think, to do with his own weirdly various background - his mother was from an old Catholic family; his father was illiterate, but nevertheless rose to the position of alderman. Shakespeare himself set out to be an actor - which was really a low-rent type of career - then rose to become court playwright. So, for all these reasons, he's very difficult to 'get at'; you never quite know which, if any, of the opinions expressed in his plays are his own. What we'll never know is whether that political 'shape-shifting' was pragmatically assumed as a sort of fire insurance to allow him to say outrageous things."
Above all, says Schama, it is Shakespeare's "sprawling, messy, virtuoso abundance" that speaks, still, to modern sensibilities. "It's really about the bagginess of life. I think that when you immerse yourself in Shakespeare, when you come out the other end, it's not only philosophically illuminating, it makes you think again about loyalty, friendship, love, desire, danger, guilt, betrayal - all those things that make us human. You also feel you've had this huge banquet of life pass through - you almost bodily pass through you - and that is a fantastic thing. Nothing, but nothing is kept back."
"If anyone still thinks the English are repressed, Shakespeare is the retort!"