The subtle and ambiguous way in which Henryson adapted and juxtaposed material from a diversity of sources in the tradition and exploited anthropomorphic conventions to blend human characteristics with animal observation both worked within, and pushed the bounds of, standard practice in the common medieval art of fable re-telling. Henryson fully exploited the fluid aspects of the tradition to produce an unusually sophisticated moral narrative, unique of its kind, making high art of an otherwise conventional genre. Internal evidence suggests that the work was composed in or around the 1480s.