A proem is a short introduction, in verse, to the matter and meaning of the rest of the poem. Some published editions of the poem do not make a division between The Proem and The Dream. The Proem is lines 1 through 290, and The Dream is lines 291 through 1334, the end of the poem.
In The Book of the Duchess, the poet is introduced in the first person. He has difficulty getting to sleep and has not slept, he says, for eight years. He reaches for a copy of a "romaunce" (a word describing the Metamorphoses of the ancient Roman poet Ovid) and reads the tale of King Seys and Queen Alcyone.
The king goes across the sea on a ship, and a storm arises and drowns all aboard. Queen Alcyone, anxious at home and awaiting his return, sends to the east and west looking for him. Until she knows the king’s fate, she will not eat bread. Distraught, she prays to Juno to send her a dream that would tell her of the fate of Seys. Juno immediately sends Alcyone to sleep, and he sends a messenger to Morpheus, the god of sleep. Morpheus is to go to the Great Sea (the Mediterranean) and enliven the king’s drowned body with his own spirit. This reanimated corpse he should send to Alcyone to speak to her and show her he has drowned.
Juno's messenger goes to the dark valley where the gods Morpheus and Eclympasteyr sleep. He rouses Morpheus, who does Juno's bidding and conveys the dead Seys to speak to his wife Alcyone. In her dream, Alcyone sees Seys at the foot of her bed, and he tells her that he has died and that she must find his body by the sea and bury it. He also tells her not to remain in sorrow too long. He adds that she was his true love in life. With "To lytel while oure blysse lasteth" [too little while our bliss lasts] (line 211), he leaves her, echoing a theme of this and other poems in Chaucer's love-poetry oeuvre. Alcyone awakens, and Seys is gone.
The narrator now reflects how helpful it would be to have the god of sleep come and give him much-needed rest himself. He describes the offering he would make to Morpheus and to his goddess, Juno: an elaborate bed of doves' down, with striped gold and black satin and linen from Reynes. He would give this gift to obtain the swift and deep sleep that Alcyone did when Juno answered her prayer.
The narrator then falls asleep on his book and experiences so strange and wonderful a dream that, he says, no one on earth can properly interpret it. Not even the famous Biblical interpreter of dreams, Joseph, who read dreams for Pharaoh (see Genesis, Book 41), nor Macrobius, the late Roman author who wrote a famous (in Chaucer's day) commentary on Cicero's Dream of Scipio, would have the skill to read the fantastic dream the narrator had that night.
Burying the body of a relative with proper rites was a recurring theme in classical literature (such as in Sophocles' play Antigone), so it was not surprising that Ovid would make it part of the story of Seys and Alcyone. It was believed by the ancient Greeks (and held as a pious belief by the ancient Romans, although by Ovid's time it was probably considered more of a superstition among the educated classes) that if a body wasn't buried properly, the departed's soul would not rest. Therefore, the living were required to treat the dead properly, and the prevention of survivors from doing so was the instigation of dramatic crisis in many works of classical literature.
The narrator's slightly humorous description of the gift he would give the god Morpheus is a parallel to the pious offering that Alcyone makes in her prayer to Juno. Alcyone asks Juno to give her news of her lost husband, and in return Alcyone will give to Juno "sacrifise/And hooly youres become I shal/With good wille, body, herte, and al:" (lines 114-116)—in short, to become the goddess's acolyte. Since Juno was, among other things, the goddess of wives and of marriage, she would welcome a pious wife (now widow) into her service.
In the same fashion, the poet offers to Morpheus something fitted to his needs, namely a bed in which to sleep. When Morpheus is described in his dark cave, he has "good leyser for to route" (line 172; "plenty of time to snore"), so he sleeps all day and does no other work. This comedic turn shows the difference between the noble, allegorical characters in the story (Alcyone, Juno, Seys) and the realistic, human characters of the poet's world. The fact that the poet is foolish enough to assume that his offer of a gaudy bed in return for a night's sleep would carry the same weight, with Juno, as Alcyone's anguished offer of her life's service in search of knowledge of the fate of her husband, again shows Chaucer poking fun at the narrator.
However, the poor insomniac narrator receives an immediate answer to his prayer (although it is implied that he simply fell asleep while reading). Once he finally falls into a deep sleep, his dream is so fantastic that it apparently defies description. Nevertheless, in a common literary reversal, the narrator endeavors to tell the reader anyway. Here Chaucer shows off his knowledge of classical literature, mentioning two major instances of dream-visions among the ancients. The story of Joseph from the Hebrew Bible would have been known to most people through stories, but the reference to Macrobius's Latin commentary on the earlier Latin writer Cicero's Dream of Scipio was erudite. The fact that both of the dreams described in these references contained important commentary on real events foreshadows that the narrator's dream will do the same. Chaucer has now established himself as well-versed in the Latin literature held in high regard at the time, especially with his references to Ovid and classical mythology.
The proem sets the stage for the main story of this poem, the narrator's dream. It can be considered that everything that comes after the proem is the elegy for Blanche, Duchess of Lancaster, or is in praise of the poet's patron, the Duchess's husband, John of Gaunt. This slightly humorous and earthy beginning—earthy because it includes references to snoring, nakedness, and human infirmity—is a convention of this type of poetry, and it does not necessarily include any biographical details from Chaucer's life.