The Parlement of foules is a poem in three parts: the prelude before the dream, the scene in the garden of love, and the debate among the birds. Each part differs from the others in its sources, content, mode of treatment, and tone. Because of these differences many-critics have argued that the poem lacks unity. Such arguments would be more convincing if Chaucer seemed unaware of the differences and if the three parts of the poem did not, in some way, serve a common purpose. It is probable, however, that Chaucer created these differences deliberately, for he appears to have worked to heighten and exploit them. A conscious artistic purpose is behind the poem's variety. Moreover, this variety is the agent of the poem's unity; it both contains and creates the poem's ultimate meaning. To make this clear, we shall look first at some of the ways in which Chaucer sharpened the distinctions between the three parts. And then we shall consider the ways in which the parts are unified and the purpose which is served by the tripartite organization.