Of Shakespeare's ten plays about English history, the two parts of Henry IV are certainly the finest, and have held the stage ever since they first appeared. Their immense popularity is due mainly to the immortal figure of Falstaff, drinker, sponger, wit, beloved of audiences from the very first performances, the source of delight, disapproval and argument - after Hamlet, perhaps the most discussed of all Shakespeare's creations. But the two plays...