Review: LIFE IS A DREAM (LA VIDA ES SUEÑO), Barbican Theatre

René Descartes moulded the course of western philosophy by asking if dreams are indistinguishable from waking reality: how does he know he is not dreaming when he is awake? All the greatest thinkers have pondered the question. It's at the core of Plato's Allegory of the Cave. It's the first line of "Bohemian Rhapsody".

It seems harmless, but the question rips open a gaping chasm of radical scepticism that philosophers would strive for centuries to close. It's also tucked dizzyingly at the heart of this gem of 17th century Spanish theatre by Pedro Calderón de la Barca and ramped up to an illusory fever pitch in Declan Donnellan's new Cheek by Jowl production.

His vision is of a Lynchian nightmare: a single wall lines the back of the stage with the looming emptiness of the Barbican Theatre clad in darkness behind it. Characters appear through doors with Looney Tunes-like surrealism, conjured from the liminal space behind it. The stage is washed in emerald green, the same shade that blurs the line between fantasy and reality in Hitchcock's Vertigo and The Wizard of Oz. What is it about that colour that penetrates so deeply into our subconsciousness?

Philosophy may underpin the story, but Shakespearean flavours dominate it. We follow a Lear like King Basilio, magnanimous but quixotic, who decides to settle the question of his successor by naming Segismundo, his son who has been imprisoned his whole life in a tower, as heir. Having only known the four walls of his prison, the latter suddenly finds himself in a lavish world of regal pomp and circumstance, the shock of which sends him down the sceptical path that leads him to question whether it is too good to be true.

It morphs from metaphysics to moral debates in the drop of a hat, often feeling like a fully-fledged thought experiment: When Segismundo believes he is dreaming he abandons any inhibitions. He kills and sexually assaults servants without remorse. Do the weight of consequences anchor our actions? Is there such a thing as innate morality? At one point he delivers a particularly Rousseauian monologue about the nature of human freedom whilst clad in chains gazing wildly at the audience demanding a response.

The impeccably skilled troupe of performers lean heavily on physically fluid clowning to keep the production buoyant with fizzling energy. Occasional moments of deliciously self-aware audience interaction, a step into the ultimate real world, are intelligently woven into the performance's fabric. But it's the philosophy, left to hang in the air in an unfussy staging, that gives this its palpable yet subtle magnetism.

Admittedly it's not easy to digest. It runs at a dense two hours without an interval. There are a smattering of elongated sequences unpunctuated by music or movement that are as engaging as a labyrinthine treatise. This is not a disadvantage, somehow it accentuates the dream like sense of floating statis. You forget that time has passed watching it. You might even zone out and wonder if it really is all a dream. That's kind of the point.

Life is a Dream (La vida es sueño) runs at the Barbican until 16 April

Photo credit: Javier Naval