For the first half an hour of Gatz (Public Theater, to Dec. 1) , Scott Shepherd sits on a set, conceived by Louisa Thompson, that looks like a drab office of the late 1990’s. In his white-collar uniform of chinos and shirt, he reads the opening chapters of F.

Scott Fitzgerald’s most famous novel as a group of characters we presume to be other office workers drift in and out, looking at him with puzzled irritation. Hang on in there: about 30 minutes in, things start kicking off; the magic and power of Gatz —originally conceived by the Elevator Repair Service theater company 20 years ago—alternates between the simple (Shepherd’s reading is a pleasure) and complex (as actors enter the frame as characters in the novel to enact parts of the novel when other characters speak and do things). This is my third time seeing Gatz, which may seem a little crazy given how long it lasts—but it should tell you everything about how special I think it is.

With dinner breaks and intermissions, Gatz comes to eight and a bit hours total, and remains, a decade after its original Obie and Lortel Award-winning engagements, a dazzling feat of both storytelling and theater. ADVERTISEMENT The real question—and this is said with baffled admiration: How does Shepherd do it? The handsome actor holds a copy of the novel, looking at its pages. But he is not reading from it; that is part of the act.

He has memorized it all, as becomes obvious late in the play when the novel-as-prop is jettisone.