Thomas Mann once observed that “a writer is someone who finds it hard to do what others do easily”—a definitive encapsulation of the need for revision and a lesson that some would-be writers never seem to learn. By Mann’s standard, Donald Hall is a prodigy. In the title piece of “Essays After Eighty”—a collection in which aging is a major theme but hardly the only one—he claims that “some of these essays took more than 80 drafts, some as few as 30.” As for that major theme, Mr. Hall, the hardy octogenarian, moves in some pretty fast literary company—Cicero, for instance, in the consoling pages of his classic essay “De Senectute” (concerning old age) and even Shakespeare in the latter lines of the “Seven Ages of Man” soliloquy (“sans teeth, sans eyes . . . sans everything”). Mr. Hall doesn’t suffer in the comparison.

For even an accomplished writer, however, his assertions about revision, taken literally, stretch a sound point. Mr. Hall may mean that it takes 30 to 80 tweaks of a piece of writing to satisfy his quest for euphony and rhythm and the mot juste. This is the typically blunt way he puts it: “The greatest pleasure in writing is rewriting. My early drafts are always wretched.”

This is the secret pleasure that all real professionals know. In Mr. Hall’s case, the claim of 30 to 80 revising efforts is credible, given the power and precision that he brings, presumably after much labor and what painters call pentimento, or repentance, to even the most ordinary scene, whether observing birds from the window of his New Hampshire farmhouse or reminiscing about his past adventures. These include a term (2006-07) as poet laureate of the United States, when he found, happily, that office hours were not required.

For these late prose pieces we are indebted to the alleged flight of Mr. Hall’s ability to write poetry—“poetry abandoned me,” he says—though his essays often echo his poetry, especially the poignant pages of his collection “Without” (1999), a free-verse account of the decline and death of his wife, the poet Jane Kenyon. His insistence on precision reminds me of the precepts of my teacher, Phillips Russell of Chapel Hill. “Be specific” was his golden rule: A chair isn’t merely a chair; it is a Queen Anne chair with a fiddle-shaped back and a brown leather seat riddled with spidery cracks. The winter birds that Mr. Hall observes in an essay titled “Out the Window” aren’t nameless; they are juncos and chickadees, nuthatches, American goldfinches and sparrows.

Long ago, in Ann Arbor, Mich., where Mr. Hall taught English for 20 years, “the jacket pockets of men’s gray suits showed the fangs of handkerchiefs.” The squirrels raiding his bird feeder are “tree rats with the agility of point guards.” In these inventive metaphors we catch the intact voice of the poet’s absconded muse. And he is certainly right, by the way, to abhor the slack formulations now in fashion, such as “may I share my poems with you?” and people “passing” or “passing away” on obit pages, where no one is allowed to simply die.

One is tempted, among the excellences in “Essays After Eighty,” to fuss a bit about the ancient bearded author photograph on the book jacket—it feels like a consciously exaggerated pose—and about Mr. Hall’s boastful defiance of conventional health practices. He is a dedicated cigarette smoker and, glorying in “malfitness,” insists that his semi-weekly exercise routines are merely prophylactic, to avert the wheelchair. No doubt anyone who survives to write as well and as long as Mr. Hall has favorable genes to thank and ought to take better care of them. His tributes to tobacco and flabbiness seem out of tune, not because he isn’t entitled to his habits but because they are uncharacteristically ordinary. Let us also note, with mild regret, the occasional in-your-face vulgarities—“Washington’s penis,” for instance. I guess he means the patriarchal monument, about which such wisecracks occur to every passing nitwit.

Deliciously readable though it is, “Essays After Eighty,” with its sketchy allusions to earlier lives, invites complement. Fortunately, a previous autobiography, “Unpacking the Boxes” (2008), subtitled “A Memoir of a Life in Poetry,” fills the bill. It traces Mr. Hall’s lives as poet, as student (Exeter, Harvard, Oxford), as college teacher, as lover of three wives and many mistresses, and as public platform reader. His lecture audiences must have enjoyed his seemingly effortless flow of aperçus, such as: “Poetry is more erotic than fiction, which is why female poets were so rare until the mid-20th century. Jane Austen and George Eliot were permitted to write great novels, but the only great 19th century woman poet was the eccentric eremite Emily Dickinson. . . . The vast increase in the number of good women poets has coincided with sexual liberation.”

Maybe, as Mr. Hall claims, poetry is slipping away from him now. But if, as the sages say, there is a compensatory dynamic in the human spirit such that as one sense falters, another is enhanced (as the deaf are said to see more acutely), Donald Hall, if abandoned by the muse of poetry, has wrought his prose to a keen autumnal edge. It used to be said that a Parisian chef could do more with an old leather shoe-tongue than amateurs with fine cuts of beef, and Mr. Hall, likewise, touches his writing with music. Long may this defiantly “malfit,” scruffily bearded, cigarette-puffing gnome sit by that window on Long Pond and defy his lurking Nemeses. Any writer should be proud to be apprenticed to the art of which he is a master.