A tyrant in us all

The day I meet Michael Sheen, the papers are full of photos of people pulling down statues of Saddam Hussein. It's a heady time for everyone, but for Sheen - deep in rehearsal for Albert Camus' rarely performed Caligula - it's particularly fascinating.

'It's odd to be preparing a play about the madness of tyranny the week the most notorious dictator in recent memory falls from grace,' he says. 'And it's a potent context in which to see it: I'm hoping world events will give audiences a way in.'

Not just a study in the psychosis of power, Camus' play is also a dramatic expression of existentialist theory. Following the death of his sister, Caligula retreats to the desert for three days, stares into the abyss and returns to Rome convinced life is meaningless.

As emperor, he applies this notion to daily existence with ruthless economy; randomly assassinating sons, fathers, lovers. In order to be free from pain, you have to be rid of everything that matters.

'I see it as Camus' answer to Sartre,' says Sheen, who clearly knows a bit about this. 'It's Camus saying: this is what happens if you impose this particular logic on a democracy.'

It's a difficult play, wordy and clever as well as funny, but for Sheen the key to Caligula is his feelings rather than his ideas.

'Rather than deal with his grief by confronting it, Caligula chooses to free himself from it by rendering life itself absurd,' he says.

'It's important that the audience go on that journey with him. After all, we've all faced a bit of existential doubt. I want the audience to feel uncomfortable, make them acknowledge that there's a bit of Caligula in everyone.'

Redeeming unlikeable characters with a particular emotional intelligence has become a trademark for the wiry, restless Sheen. His explosive Jimmy Porter for the National in 1999 rehabilitated the boorish, angry young man as someone for whom one could feel sympathy.

The actor pulled off a similar trick with his portrait of obnoxious child prodigy Mozart in Peter Shaffer's production of Amadeus.