viz.

Austin, TX, Ghost Sign, image from Flickr

There is nothing in heaven above, in the earth beneath, in the water, or in the air we breathe but will be found in the universal Language of the Walls. ("The Language of the Walls," anonymous, 1855).

 Maps are propositions as well as indexes, making visual arguments about our orientation in this world--a good map (whether road or otherwise) gets us somewhere, forces us to reconsider the relationship between us and the world.  Advertising, that pernicious beasat, is also somewhere between sign and proposition.  A visual referent to a thing--a bottle of beer, a pack of gum, an insurance service--an advertisement also makes an argument or, at the very least, presents a fantasy of (self-)orientation.  But what happens when those relationships are obscured, when the fantasy becomes outdated?  What happens when the ad remains after the product is gone?