Piers Plowman (written 1370–90) or Visio Willelmi de Petro Ploughman (William's Vision of Piers Plowman) is a Middle English allegorical narrative poem by William Langland. It is written in unrhymed alliterative verse divided into sections called "passus" (Latin for "step"). Piers is considered by many critics to be one of the greatest works of English literature of the Middle Ages, along with Chaucer's Canterbury Tales and the Pearl Poet's Sir Gawain and the Green Knight. Piers Plowman contains the first known allusion to a literary tradition of Robin Hood tales.