By virtue of its innermost intention, and like all questions about language, structuralism escapes the classical history of ideas which already supposes structuralism's possibility, for the latter naively belongs to the province of language and propounds itself within it. Nevertheless, by virtue of an irreducible region of irreflection and spontaneity within it, by virtue of the essential shadow of the undeclared, the structuralist phenomenon will deserve examination by the historian of ideas. For better or for worse. Everything within this phenomenon that does not in itself transparently belong to the question of the sign will merit this scrutiny; as will everything within it that is methodologically effective, thereby possessing the kind of infallibil-ity now ascribed to sleepwalkers and formerly attributed to instinct, which was said to be as certain as it was blind.