By the time Shakespeare came to write Macbeth - almost certainly in 1605/1606 - he had already completed three of the great tragedies with which modern audiences are so familiar: Hamlet (1601), Othello (1603) and King Lear (1605).

Each of those plays gives us an eponymous hero who is in some significant way flawed, but for whom we also inevitably feel deep sympathy, whatever his errors or crimes. But in Macbeth Shakespeare has chosen for his tragic hero a man guilty of the most terrible crime imaginable to a Jacobean audience, that of regicide - the murder of a king.

Part of the writer's triumph is to succeed in making Macbeth, whose crime we must detest, a man in whom we must also see something of our own darker side, our own potential for evil, so that Malcolm's final judgement on him as a mere 'butcher' seems wholly inadequate, the verdict of someone who does not share the audience's insight into Macbeth's anguished inner world.