In July, 1820, John Keats published his third and final book, “Lamia, Isabella, The Eve of St. Agnes and Other Poems.” He had no reason to expect that it would be a success, with either the public or the critics: in his short career, the twenty-four-year-old poet had known nothing but rejection on both fronts. After his first book, “Poems,” appeared, in 1817, his publishers, the brothers Charles and James Ollier, refused to have anything more to do with him. In a letter to the poet’s brother George, they wrote, “We regret that your brother ever requested us to publish his book, or that our opinion of its talent should have led us to acquiesce in undertaking it.” They went on, “By far the greater number of persons who have purchased it from us have found fault with it in such plain terms, that we have in many cases offered to take the book back rather than be annoyed with the ridicule which has, time after time, been showered upon it.”

“I have an habitual feeling,” Keats wrote, “that I am leading a posthumous existence.” Illustration by David Hughes

When Keats’s long poem “Endymion” came out, the following year, from a different firm, the ridicule was even worse, and far more public. The leading Tory magazines of the day published savagely satirical reviews, linking the poem’s undisciplined exuberance with its author’s working-class origins. Keats was the son of a stable-keeper, and he had trained as an apothecary: no wonder, the critics smirked, that he had fallen in with the sentimental “Cockney School” of poets, led by the radical journalist Leigh Hunt. Keats’s class and his liberal politics were enough to damn him sight unseen, as the Quarterly Review made clear when its critic admitted that he had not bothered to read “Endymion” to the end: “If any one should be bold enough to purchase this ‘Poetic Romance,’ and so much more patient, than ourselves, as to get beyond the first book, and so much more fortunate as to find a meaning, we entreat him to make us acquainted with his success.” Blackwood’s Magazine said, “It is a better and a wiser thing to be a starved apothecary than a starved poet; so back to the shop Mr John, back to ‘plasters, pills, and ointment boxes.’ ”

After all this, Keats could hardly have been optimistic about his third volume. He grumbled in a letter to George that he ought to give up writing and become a doctor—it couldn’t be any “worse than writing poems, & hanging them up to be fly-blown on the Review shambles.” But he must have been particularly unsettled by a review in the Literary Chronicle and Weekly Review. The book was not mocked; the anonymous critic simply said, more in sorrow than in anger, that it was not much good. “We confess this volume has disappointed us; from Mr Keats’s former productions, we had augured better things,” the paper opined. “We are confident he can do better.”

To Keats, this would have been the bitterest verdict of all, for by the summer of 1820 he knew that he would not live to publish another book. Tuberculosis was slowly choking him to death, leaving him without the will or the energy to work: he had written almost no poetry since late the preceding year, and would write no more before he died, in Rome, in February, 1821. Keats continued to believe that, with time and study, he would have become a great poet, but he was starting to agree with the critics that nothing he had written could prove it. A year before his death, he wrote that he was reconciled to failure: “ ‘If I should die,’ said I to myself, ‘I have left no immortal work behind me—nothing to make my friends proud of my memory—but I have lov’d the principle of beauty in all things, and if I had had time I would have made myself remember’d.’ ”

Of all the piteous elements in Keats’s story, none is more distressing than the idea that he went to his grave convinced of his failure. For Keats’s last book, in addition to the three masterpieces named in its title, included a series of odes—“Ode to a Nightingale,” “Ode on a Grecian Urn,” “Ode to Psyche,” “Ode on Melancholy,” and “To Autumn”—that are now universally regarded as among the greatest poems in the English language. If any single book ever earned its author immortality, it was this one. And, as Stanley Plumly points out in “Posthumous Keats” (Norton; $27.95), his moving new study of the poet’s work and legend, “one could form a considerable collection from what was left out of this last book.” Some of Keats’s best poems, including “La Belle Dame Sans Merci,” were never collected in his lifetime.

Did Keats really believe that, having written such poems, he was a failure? The question is more urgent in his case than in any other poet’s, for no writer ever yearned for fame more ardently than Keats. His ambition was all the more remarkable considering that he started life with none of the advantages of the noble Byron or the wealthy Shelley. Born in 1795, the eldest child of a prosperous working-class family, he soon learned how precarious his fortunes really were. His father, Thomas, died in a riding accident when Keats was eight years old, a blow made worse by the remarriage of his mother, Frances, just a couple of months later. The hasty marriage was brief, and when it collapsed Frances disappeared in a cloud of scandalous rumors, leaving her children in the care of their grandmother. When she came back home, a few years later, it was to die. John nursed her through the final stages of consumption, as he was to do with his youngest brother, Tom, in 1818.

Keats, orphaned at the age of fourteen, was not entirely without resources. A small legacy paid for his apprenticeship to a surgeon, after which he went on to medical school, leaving in 1816 with a license to practice as an apothecary—the lowest, most menial kind of medical man. But by then he had decided that poetry, not medicine, was his calling. In the time remaining to him—less than five years—he lived off the remains of his inheritance in order to devote himself to greatness.

From his first mature poem, the sonnet “On First Looking Into Chapman’s Homer,” written just before his twenty-first birthday, to his last—the dreamlike fragment “The Fall of Hyperion,” which he abandoned just before his twenty-fourth—this ambition was Keats’s major theme. In that first poem, written in the early-morning hours after a night spent reading Homer with friends, Keats evokes his dawning sense of the immense realm of poetry—“like stout Cortez when with eagle eyes / He stared at the Pacific”—and of the heroic effort required to carve out for himself one of the “goodly states and kingdoms” which “bards in fealty to Apollo hold.” In the last, he records a hallucinatory encounter with the goddess Moneta, who tells him that his quest has failed, that he is not a poet but a mere dreamer:

The poet and the dreamer are distinct, Diverse, sheer opposite, antipodes. The one pours out a balm upon the world, The other vexes it.

Keats offered an apparently unambiguous assessment of his short career when he told his friend Joseph Severn—a young painter who volunteered to accompany him to Rome, and nursed him through his last months—that he did not want his name to appear on his tombstone. Instead, he instructed, it should simply read, “Here lies one whose name was writ in* water.” Yet Plumly, an award-winning poet, is deeply attuned to the subtleties of poetic ambition, and he points out that the famous epitaph is not quite as resigned as it seems. “The fact that Keats did not want his name to appear on the tombstone adds only interest to the mystery of who might be buried so anonymously,” Plumly writes. “The unnamed is, after all, written in stone, not water.” It is the epitaph not of a man accepting oblivion but of a poet cultivating his legend from beyond the grave. Plumly quotes Keats’s publisher John Taylor, who approved of the anonymous gravestone because he foresaw “that it will be as clear an indication to posterity as the plainest, everyday inscription that one may find in Westminster Abbey.”

Such moments of canny sympathy justify the unusual approach that Plumly takes in “Posthumous Keats.” Instead of simply recounting the life and analyzing the poems, Plumly pursues his intuitions through a series of linked essays, all of them concerned with aspects of the poet’s death and afterlife. He explores the “drawings, paintings, engravings, and sculptings” of Keats’s face “by some forty separate artists,” showing how he was turned into the Victorians’ archetypal poet, “perfected and abstracted” into unrecognizability. He narrates Keats’s last days in Rome, evoking the eerie contrast between the sensual city and the increasingly incorporeal sufferer. He shows us Keats running into Coleridge on Hampstead Heath, and quotes the older poet’s prophecy: “When I shook him by the hand there was death!”

Through this interweaving of themes and episodes—a “walk around in Keats’s life and art, not simply through them”—Plumly emphasizes, as a more conventional biography never could, the fatal, fated quality of Keats’s career. He shows how Keats, in a way that feels unique even among the doomed Romantics, became posthumous while he was still alive. In one sense, this is because he knew that he was dying long before death arrived. Thanks to his medical training, and to his experiences nursing his mother and his brother, Keats was well acquainted with the symptoms of tuberculosis. On February 3, 1820, when he fell into a coughing fit and brought up blood on the sheets, he had no doubt what was in store. “I know the colour of that blood. It’s arterial blood,” his friend Charles Brown remembered Keats saying. “That blood is my death-warrant. I must die.”

For the next year, Keats went along with his doctors’ various treatments—bloodletting, starvation diets, complete avoidance of excitement. He agreed to leave England, on the slight chance that Italian air would cure him. But he could never trick himself into believing that his first, fatal diagnosis was mistaken. In November, 1820, in the last letter Keats wrote, he told Brown, “I have an habitual feeling of my real life having past, and that I am leading a posthumous existence.”

Keats is hardly the only nineteenth-century writer to have died a lingering, consumptive death; what sets him apart is that his art, from the beginning, was connected with the imagination of death, especially his own. Like Socrates, he could have said that his life was a long preparation for death, so often had he written about it in poems and letters. Keats’s “posthumous existence,” one might say, began at the moment he became a poet.

That is why, after he died, so many of his lines began to look eerily like premonitions. In “Sleep and Poetry,” an early attempt at a long poem, Keats was already bargaining for time to complete his work: “O for ten years, that I may overwhelm / Myself in poesy; so I may do the deed / That my own soul has to itself decreed.” By the age of twenty-one, he was imagining what it would be like to lie in his grave:

If I do fall, at least I will be laid Beneath the silence of a poplar shade; And over me the grass shall be smooth shaven; And there shall be a kind memorial graven.

The union of poetry and death, in Keats’s work, only became more intimate as his powers grew. In March, 1817, shortly after the Parthenon marbles taken from Greece by Lord Elgin had been put on display at the British Museum, the painter Benjamin Robert Haydon took Keats to see them. A day or two later, Keats recorded his impressions in a sonnet that invokes death in its very first line:

My spirit is too weak—mortality Weighs heavily on me like unwilling sleep, And each imagined pinnacle and steep Of godlike hardship, tells me I must die.

Why should the sublimity of these images immediately have reminded Keats that he must die? One might as well ask why he exclaimed, in another poem, “Verse, Fame, and Beauty are intense indeed, / But Death intenser.” Or why, in one of his last poems, a love sonnet, he yearned “Still, still to hear her tender-taken breath, / And so live ever—or else swoon to death.”

It would be easy to explain Keats’s preoccupation with death by assigning it a straightforward biographical cause. Many biographers and critics have pointed to the early loss of his father, and to his bedside view of his mother’s and brother’s slow deaths. Then, there was his experience as a student at Guy’s Hospital, in London, where he attended gruesome surgeries and dissections. To an extent unusual even by the grim standards of his time, Keats was constantly surrounded by death and dying. It was only rational for him to wonder if he, too, would die young. This was, in fact, the subject of one of his most moving sonnets—the one that begins, “When I have fears that I may cease to be / Before my pen has gleaned my teeming brain.”

Plumly unsparingly relates the bodily reality of Keats’s sickness and death. His description of the poet’s last days is as clinical as anything Keats might have observed while walking the wards: