A Platonic dialogue in the form of a double anachronism--the action takes place two centuries after our era--Joseph Brodsky's only play, Marbles, is set in a prison cell that alone provides for the three unities of classic drama: those of time, place, and action. A nightmare rather than a utopia, this play proceeds according to the immanent logic of mental aggravation as its two characters, the inmates Publius and Tullius, examine the tautology...