Many of Chaucer's major works before the Canterbury Tales are written in the so-called ‘dream-vision’ form derived from French tradition, where, as in the Romance of the Rose, the narrator recounts his falling asleep and his subsequent dream, the subject of which is principally the pleasures and travails of love. Chaucer's dream-visions are nothing like the length of the Rose, of course, but, if we compare them with their shorter French sources, we see how Chaucer extends the form to cover weighty philosophical matters like mortality and consolation, the status of textual authority, and the place of human sexuality within the natural order. This thematic enriching is synonymous with the form being used to explore problems rather than reach conclusions; indeed, two of the dream-visions, the House of Fame and the Legend of Good Women, literally have no conclusion and the two that are finished, the Book of the Duchess and the Parliament of Fowls, have endings whose emphatic closures only point up the fact that no solution has been found to the questions posed.

This is apparent if we compare the Book of the Duchess, Chaucer's earliest ‘major’ poem, with its principal source, Machaut's Judgement of the King of Bohemia. Modern readers are often horrified at the discovery that the portrait of Blanche, Duchess of Lancaster (whose elegy this poem is), is based closely in some respects on the grieving knight's lady in the Machaut, as if the poem's ‘sincerity’ is thereby impugned, though it is always easier to spot the conventions governing earlier ‘portraiture’ (be they in medieval text or tomb effigy) than those governing our own. The Machaut poem is essentially a debate over whether a lover who suffers loss through the partner's death is in more pain than one who suffers through infidelity; at the end of the poem the two lovers put their cases to the king, who, guided by the allegorical figure of Reason among others, solves the problem by finding on behalf of the betrayed lover's greater pain, a verdict universally accepted. Everyone goes off, the lovers included, happy with the arbitration.