Preoccupied, perhaps misled, by the sensationalism of his plays and novels, too many thinkers, American and British alike, have left unread and unexamined Sartre's magnum opus l être et Le Néant. Such attention as the book has received has been directed for the most part to criticism of Sartre's categoreal structures and to the dissection of his phenomenological analyses.¹ But as regards the cogency of the epistemology which the work argues, and of the metaphysics which this epistemology presupposes, there is in English virtually nothing.