But no less evidently such pictorial aggregation offers little to preaching, since it has no vigor of composition. To be moving, allegory as well as higher symbolism must be narrative. The classic demonstration of this, the _Pilgrim’s Progress_, was written by a preacher. The art has never been more widely or more expertly pursued than in the middle age. The fourteenth-century English _Piers Plowman_ suggests even more vividly, with its strongly oral manner, how allegory might move in preaching. A sermon might be not only enlivened by passages of easily recognizable description; it might further be vivified by making the figures individuals and by putting them into speech and action. A complete demonstration is furnished in the interlude, prologue, and tale of Chaucer’s Pardoner. That accomplished rascal is made to display the whole art of oral narrative, from its vulgar drama to its high ranges of symbolic suggestion. The case is extreme; but the method has been a resource of popular preaching from the days of Nathan’s rebuke to David down to the present. Oral narrative, often with dramatic dialogue, has been heard again and again, both in such base uses as the Pardoner’s and in such urgency of message as Bunyan’s, because it has been found surely persuasive. Here is the high art of the _exemplum_. Often the medieval record puts us off with a summary; sometimes the manuals give a mere note, “Tell the story of so-and-so”; but sometimes there are clear clues to such narrative art as makes the Pardoner’s tale breathless. An _exemplum_ of Walter Map’s lets us divine how dramatic the tale might be in the pulpit.