A broken mind is a terrifying notion. Once gone, so too, has a large slice of the humanity. Isn’t that why we hurry past the insane, with their babbling interior monologue, on the street? It’s a brave playwright who subjects an audience to the mad jabbering of a fractured mind, delivered relentlessly  at the speed of thought for a dozen minutes. And in the pitch black, with only the speaker’s mouth illuminated. Samuel Beckett, who was many things, was nothing if not a courageous writer. Beckett’s Not I, a powerful and unsettling portrait of the isolation of madness, returned to…