Provides a brief history of the dream vision, from biblical, classical, and medieval sources, as these relate to an understanding of PPl. Finds greatest influence in the Bible: prophetic visions are especially relevant in their serial nature, their use of an instructive figure, and the narrative device of the tour. The apocryphal books developed the tradition of visionary allegory by adopting series of visions and dialogues (as in Zachariah) and tours, devices later used in visionary narratives of the other world. Plato’s myth of Er, indirectly known to the medieval Latin west, offered a narrative of serial nature, various potentiae, a moralized landscape, personifications, and a representation of justice at the eschaton. Although Prudentius’s Psychomachia is not a vision, personified vices are presented in an “apocalyptic” struggle in a fashion that influenced much later writing. The learned tradition of Platonic visionary allegory (e.g., Boethius and Martianus Capella) offered impetus in the Middle Ages to literary forms such as dialogue, celestial flight, the allegorical marriage, moralized landscapes, the labeled edifice, the pilgrimage. French allegory provides an immediate background, rather than direct sources, for PPl. The Songe d’Enfer, a dream vision, established in French the tradition of the voie, which features a visionary account of a pilgrimage, often through an allegorical landscape, and contains elements of satire. Such voies set the pattern for most of the allegorical forms in French and English poems. Outside this tradition, Li Tornoiemenz Antecrist, though not a dream poem, presents a psychomachia of virtues and vices that features Antichrist and contains an allegory of the body as a castle and an allegorical banquet. Le Roman de Fauvel, besides presenting the character Fauvel, also features a marriage of personifications that resembles the Meed scene. The English tradition preceding PPl is too thin in its extant remnant to account for WL’s knowledge of traditional material, much of which may have come to the poet through sermons.