To spare himself the trouble of organizing and publishing the richest part of his prose, Pessoa invented The Book of Disquiet, which never existed, strictly speaking, and can never exist. What we have here isn’t a book but its subversion and negation: the ingredients for a book whose recipe is to keep sifting, the mutant germ of a book and its weirdly lush ramifications, the rooms and windows to build a book but no floor plan and no floor, a compendium of many potential books and many others already in ruins.

–Richard Zenith, from his Introduction to The Book of Disquiet