Less a show than a play and less a play than a meditation, 11 and 12, Peter Brook’s production of a religious dispute over the number of times a prayer should be recited, is the exact opposite of epic theatre. It’s a whisper in the dark that creeps into your bones and unsettles you with its intellectual purity.

It’s the sort of Brook show that makes you think you’re not really good enough to live in the world, let alone go to the theatre. It eschews any noise or abrasion. It is beautifully done and exquisitely lit. It expresses quiet horror at the thought of warfare and massacre stemming from one little prayer bead. And it chills the blood, not warms it.

The simple spirituality in Brook’s work is a complex map of mystical journeys and undertakings. But no other director could create a scene in which the colour of excrement is discussed, with turds and toilet paper, and make it not only inoffensive, but almost charming.

The doctrinal dispute is told in the form of a third person narrative fable, adapted by Brook’s longstanding collaborator Marie-Helene Estienne from the work of Amadou Hampate Ba, whose book Tierno Bokar is the source of both this piece and its precursor seen here a few years ago.

Brook is drawn to the issue of the place of religion in everyday life, not to draw moral conclusions, but to live through frightening contradictions.

His mixed-race actors – American, Palestinian, African, Spanish and French, with a Japanese musician (Brook’s regular accompanist, Toshi Tsuchitori) who sits on the side of the red strips of carpet with a battery of drums, xylophones, and wind instruments – are themselves the embodiment of tolerance and collaboration that the whole project represents; it is co-commissioned by the Barbican, Brook’s own Bouffes du Nord, and the Grotowski Institute in Wroclaw.

I just wish I could love the 100-minute show as much as I admire it, even though lines like “God is the embarrassment of the human mind” test one’s patience for a second or two. But, again, no other director can take the cliché of a boat ride in an improvised hammock of red silk and make that work, too. And but still more, while the issues are super-humane, the atmosphere is a little too pious for total comfort. Which is probably what Brook is aiming for.