Pessoa invented multiple fictional authors, called "heteronyms," each with their own biography, style, and philosophy: Alberto Caeiro the naive pantheist, Ricardo Reis the Horatian classicist, Alvaro de Campos the Whitmanesque modernist, and Pessoa himself the melancholy metaphysician. The result is a one-man anthology that also constitutes a meditation on identity's fundamental instability. Richard Zenith's translation opened Pessoa to English readers.

The case for it, the case against, and the rest of the canon open with Pro.