Wilson and Rollyson both make heavy use of Plath’s archived letters and journals, committing themselves thereby to chunks of laborious paraphrase: “In an unpublished letter,” Wilson tells us at one point, “she outlined her belief that, at the moment, her store of suppressed sexual energy was being sub­limated, channelled into her creativity.” Zzzz. This sort of thing, as it accumulates, produces a muffling, third-hand effect. Another breath from the Plath-world, maybe: mummification.

The best books about Sylvia Plath (no shock here) are by women: Janet Malcolm’s probing, felineThe Silent Woman and Diane Middlebrook’s Her Husband. But her best critic, strange to say, was Ted Hughes. Hughes on Plath is irresistible, not merely because he was a genius writing about a genius, but because the force propelling his prose is love. In the letters and essays that he wrote about his dead wife, Hughes responded to her work with a binocular combination of spousal sympathy and undomesticated awe. “Behind these poems,” he wrote in a 1965 essay on Ariel, “there is a fierce and uncompromising nature. There is also a child desperately infatuated with the world. And there is a strange muse, bald, white and wild, in her ‘hood of bone’, floating over a landscape like that of the Primitive Painters.” This is deep-focus concern, with nothing retrospective or after-the-fact about it. Middlebrook has persuasively demonstrated that the Plath-Hughes marriage was on one level a devoted mutual artistic stewardship, in which each party saw very clearly the nature of the other’s gift.

Their daughter, Frieda Hughes, in her foreword to the 2005 edition of Ariel, writes of the arrival of “the distinctive Ariel voice,” an explosively liberated poetic voice that, after a breakthrough in late 1961, would appear “with increasing frequency, ease, and ferocity.” Of the liberation there can be no doubt, but it seems to me that Ariel has more than one voice. There’s the voice of the heavy-metal showstoppers like “Daddy” and “Lady Lazarus”—profane, bombastically crazy—but there’s another voice too, a quieter voice that mutters as if entranced: “The comets / Have such a space to cross …” The beginning of “Cut,” meanwhile, detours into the bruising Salingerian deadpan of The Bell Jar: “What a thrill— / My thumb instead of an onion. / The top quite gone / Except for a sort of a hinge.”

The book’s impact, nonetheless, is total. In visions and maledictions, and weird singsong, the poems straggle across the page like disemboweled nursery rhymes. “Flapping and sucking, blood-loving bat. / That is that. That is that.” Some of them she wrote in a cold London flat between the hours of 4 a.m. and 8 a.m., with her children asleep in the next room and her husband off with another woman. Haloed with fatigue, she aimed herself straight at the unthinkable. “But my god, the clouds are like cotton. / Armies of them. They are carbon monoxide.” She seems at times to be talking to herself, testing her own nerve. Some kind of terminus confronts her: a magnetic white deadness, fury at the freezing point. “How far is it? / How far is it now?” And the outcome of this confrontation—­thrillingly, horrifyingly—is in the balance. It’s the unrepeatable sensation of Ariel.