Thirty years ago Roland Barthes and others first perceived the power of unassertive objects as "signs," bearers of accepted opinion and of ideological manipulation. In the three decades since, there has developed a new science of signs, called semiotics. Its practitioners include advertisers, politicians, media pundits, and cultural mandarins, all of whom send signals--a product, an image, a service, an idea--to those who will "buy" only...