Like ASTONISH YOURSELF!, here is another fascinating book and author. Fernando Pessoa had all of the personas he inhabited write their own poetry and prose "in character". The works are all very different from each other.
ALWAYS ASTONISHED: Selected Prose by Fernando Pessoa
An excellent introduction to this esteemed Portuguese poet's work, including his influential essay, "On Shakespeare." Pessoa is of special interest in the authorship debate because his fame is linked to the "heteronyms" (Alberto Caeiro, Ricardo Reis, and Alvaro de Campos) under which he also wrote and published. He has described "heteronyms" not merely as "pseudonyms," but as other characters/personalities that live inside him. "After looking for him in the poems, we search for him in the prose. The pursuit of the Other in Pessoa's work is never-ending," writes Edwin Honig (the translator and editor of Always Astonished) in his Introduction. In Always Astonished Pessoa and his several selves (Caeiro, Reis and de Campos) discuss one another's work, revealing how Portuguese modernism was shaped. "To pretend is to know oneself," Pessoa once wrote.
ALWAYS ASTONISHED is published by and available from City Lights.