Nearly a century after his wrenching death, the Portuguese poet Fernando Pessoa (1888-1935) remains one of our most enigmatic writers. Believing he could do “more in dreams than Napoleon,” yet haunted by the specter of hereditary madness, Pessoa invented dozens of alter egos, or “heteronyms,” under whose names he wrote in Portuguese, English, and French. Unsurprisingly, this “most multifarious of writers” (Guardian) has long eluded a definitive biographer — but in renowned translator and Pessoa scholar Richard Zenith, he has met his match. Relatively unknown in his lifetime, Pessoa was all but destined for literary oblivion when the arc of his afterlife bent, suddenly and improbably, toward greatness, with the discovery of some 25,000 unpublished papers left in a large, wooden trunk. Drawing on this…