The multifaceted and labyrinthine oeuvre of the Portuguese poet Fernando Pessoa (1888-1935) is distinguished by having been written and published under more than seventy different names. These were not mere pseudonyms, but what Pessoa termed 'heteronyms, ' fully realized identities possessed not only of wildly divergent writing styles and opinions, but also of detailed biographies. In many cases, their independent existences extended to their publication of letters and critical readings of each other's works (and those of Pessoa 'himself').

Long acclaimed in continental Europe and...