Though he has been a director for 70 years, Peter Brook doesn’t like to call himself that. He prefers “distiller”: someone who boils away everything extraneous to render the essence of the story he’s telling.

That’s quite a dramatic expression of precision (or modesty) for one of theater’s indisputable greats. And yet, as applied to “Why?” — the new work written and staged by Mr. Brook and his longtime collaborator, Marie-Hélène Estienne — the word “distiller” seems apt. Taking the play in is like sipping a rarefied eau de vie, the kind that scalds as it cools.

Which is to say that “Why?” — which opened on Thursday at the Polonsky Shakespeare Center in a production from the Théâtre des Bouffes du Nord in Paris presented by Theater for a New Audience in Brooklyn — is both plain and sophisticated, in ways that for some people will cancel each other out. Its first half is abstract, theoretical: an exploration of the meaning and means of theater itself. The second half is all concrete, focusing on what happens when those meanings and means are misused.