Fiona Sampson’s new biography has nine chapters, or “books”—in imitation of her subject Elizabeth Barrett Browning’s masterpiece, Aurora Leigh (1856). At the top of the ninth, Sampson writes: “Now things begin to speed up.” To which the reader replies, “At last!” After the somnolent pace of the preceding chapters of Two-Way Mirror, this one downright hums. It covers the final eight years (1853–1861) of Barrett Browning’s eminently Victorian life, a period in which she wrote and published her verse novel to wide acclaim, dallied with séances, watched Robert Browning rise in literary esteem, bore the vicissitudes of Italy’s struggle for independence, and mourned the successive losses of her beloved spaniel, her estranged father, and her former mentor Mary Russell Mitford. By the time we get to Barrett Browning’s own death in 1861 at fifty-one, in the arms of her husband Robert, even students of her poetry will feel they have only begun to know her—so long has it taken for Sampson’s subject to come to life. By combining in a single chapter so many matters of personal, political, and literary import, Sampson at last allows actions and not reflections to prevail. This choice makes for a more arresting narrative than in previous chapters, and it allows her to get away with statements that would be risible had they appeared earlier, strewn among the indulgent asides that characterize the rest of Two-Way Mirror:

Sometime after 4 a.m., Robert asks her if she knows him and she