There are no American flags in the Jasper Johns exhibition at the National Gallery, no painted maps or bronzed ale cans. Targets are the theme, and Target is the sponsor. The first room looks like a shooting gallery. The two big targets of 1955, one with four plaster faces arrayed in boxes and one with miscellaneous body parts, are right in range. The Museum of Modern Art owns one of these trophy pictures, and David Geffen owns the other; a revelation when they were first exhibited and understood as "cool" rejections of emotive Abstract Expressionism, they now look stiff and forlorn hanging on the wall. The organizers of the show want us to take a fresh look at Johns' greatest decade of work, 1955 to 1965. What Johns was up to, they argue, is an ongoing "Allegory of Painting," as targets yielded to related motifs. In other words, this is art about art, just as critics back in the 1970s argued that Hitchcock's films were really about shooting movies. (Come to think of it, Johns' four faces may recall Mount Rushmore, with Cary Grant hanging on for dear life in North by Northwest.) But why targets? Take a closer look at the upper right corner, under the fourth nose, for a possible clue.