The god Hermes (Mercury), having fallen deeply in love with a nymph who has hidden herself from him, hears a voice complaining of being imprisoned in a snake's body. The speaker is a beautiful serpent. She tells Hermes that she knows he seeks a nymph and offers to make the nymph, to whom she has given the power of invisibility, visible to him providing he will restore to her her woman's body. Hermes gladly agrees. The nymph becomes visible to Hermes; the serpent turns into a beautiful woman and disappears.
Lamia, the serpent-turned-woman, while in her serpent state, had the power to send her spirit wherever she wished. On one of her spirit journeys she had seen a Corinthian youth, Lycius. Now, as woman, she reappears and stands at the side of a road along which she knows Lycius will come on his way to Corinth. When he arrives, she addresses him, asking him if he will leave her all alone where she is. Lycius looks at her and at once falls violently in love with her. Together they walk to Corinth and make their abode in a mansion which she leads him to. There they live together as man and wife, avoiding the company of others.
Lycius and Lamia live happily in the blisses of love until Lycius decides they ought to marry and invite all their friends to the marriage festival. Lamia is strongly opposed to this plan, but the persistence of Lycius at last wins her reluctant consent. She agrees on the condition that Lycius will not invite the philosopher Apollonius to the marriage feast.
While Lycius is absent inviting all his kinsfolk to the wedding, Lamia, with her magic powers, summons invisible servants who decorate the banquet room and furnish it with rich foods of every kind. When Lycius' guests arrive — Lamia has no friends or relatives in Corinth, she tells Lycius — they marvel at the splendor of the mansion. None of them had known that there was such a magnificent palace in Corinth. Among the guests is Apollonius, who has come uninvited.
At the height of the wedding feast, Apollonius begins to stare fixedly at Lamia. Lamia grows pale and exhibits extreme discomfort. She makes no answer to Lycius' agonized questions as to what ails her. The feasting and the music come to a stop. Turning to Apollonius, Lycius commands him to cease staring at Lamia. "Fool," answers the philosopher contemptuously, "from every ill / Of life have I preserv'd thee to this day, / And shall I see thee made a serpent's prey?" Looking at Lamia again, he utters two words: "A serpent!" At the words, Lamia vanishes. At the moment of her disappearance, Lycius dies.
Lamia is the last of the four metrical romances written by Keats. Its source is a short anecdote in Robert Burton's Anatomy of Melancholy that Keats appended at the end of the poem. As Keats was intending to write a poem that would have popular appeal in Lamia, it is possible that his intention was merely to expand the anecdote into a lengthy tale by means of the rich sensuous detail which is the special hallmark of The Eve of St. Agnes. Lamia has puzzled critics because of the elusiveness of its theme. Lamia seems to say that passionate love is an illusion and an enchantment, ultimately destructive. On the other hand, Keats' attitude toward his characters is somewhat ambiguous. Lamia is not entitled to human love because she is not human; she is a serpent. She has deceived Lycius. She must be kept a secret. She has no family, no parents. She does not want Apollonius invited to the marriage because she fears he will expose her. Nevertheless, Keats presents her sympathetically; she is not an evil creature.
Lycius too is presented sympathetically but in living with Lamia he is indulging in "sweet sin." Since he is a high-minded Platonist when first introduced into the story, his love for Lamia is indulging a weakness. When Lycius and Lamia meet Apollonius, Lycius' mentor, while walking through Corinth, Lycius is at pains to avoid being recognized by him.
In lines 375-76, Part I, Lycius calls Apollonius "my trusty guide / And good instructor" and in lines 296-97, Part II, Apollonius makes the claim that "from every ill / Of life have I preserv'd thee to this day." Yet Apollonius in the story seems malignant and scornful of Lycius, whose death he is indirectly responsible for.
Keats may be presenting a situation dramatically in Lamia, showing the good and the bad, and not coming to any final judgment. But he seems to be doing more than that. The subject of Lamia is consuming love such as Keats himself was experiencing when he wrote the poem. His letters to Fanny Brawne indicate that he was obsessed by her beauty — and, at the same time, fearful for his freedom. He realized, however, that desire must be curbed by restraint, that love must harmonize with, and be a part of life, rather than dominate and control it. Lamia, therefore, can be regarded as a warning against the all-absorbing nature of illusory, passionate love and a recognition of the claims of reason.
The reason why Lamia is usually not included in the first rank among Keats' poems may be that the story it tells is not of absorbing interest. It lacks suspense, but in this respect it is not inferior to The Eve of St. Agnes, which also has relatively little suspense. Neither poem has much in the way of crisis and climax. Keats makes more use of dialogue in Lamia than in The Eve of St. Agnes, and in this area his narrative technique is superior, but this is to be expected since Lamia has more characters than The Eve of St. Agnes. The great advantage that The Eve of St. Agnes has over Lamia is that it is about human lovers. A tale about the love between a supernatural creature like Lamia and a human being may have romantic strangeness but it does not have much human interest. In richness of description, however, Lamia is probably as good as anything Keats wrote. Lamia-as-snake is as beautiful as Lamia-as-woman:
She was a gordian shape of dazzling hue,
Vermilion-spotted, golden, green, and blue;
Striped like a zebra, freckled like a pard,
Eyed like a peacock, and all crimson barr'd;
And full of silver moons, that, as she breathed,
Dissolv'd or brighter shone, or interwreathed
Their lustres with the gloomier tapestries. (I, 47-53)
Just as in The Eve of St. Agnes Keats concentrated on the stained glass window in order to emphasize the loveliness of Madeline, so in Lamia Keats devotes many lines of description to the banquet hall in the palace of Lamia and Lycius in order to emphasize their tragedy, for it was there that Lamia vanished and Lycius perished. The banquet hall is the setting of the climax of the story.
For his last narrative poem, Keats used the iambic pentameter couplets of Endymion, but he shows a much greater mastery of his couplets in Lamia than in Endymion. He does not let the rhymes control the sense, and the lines flow on so smoothly that the reader is almost unaware of the rhymes. To vary his couplets, he uses triplets and iambic hexameter lines.