Donald Lipski and Buzz Spector are both well known for their use of found objects in creating sculpture. However, it is not the objects but the meanings associated with them that are the real materials of their work. Spector's loaves of bread connote nourishment, warmth and community; his roses, passion and love. Lipski's flags symbolize patriotism, America and the divisive controversy over the protection of the flag itself. The unaccustomed situations in which these artists put such culturally loaded objects create an enigmatic tension from which a leap of understanding may occur.

Organized by Terrie Sultan, curator of contemporary art, their show at the Corcoran is titled "Transgressions." As if to heal the Corcoran's own scars from the Mapplethorpe controversy, which began here in 1989, this show makes an aggressive thrust toward awakening us to the implications of everyday symbols. The urge to expand understanding has suffused art throughout this century. In her rather abstruse catalogue essay, Sultan writes of pushing boundaries by transgressing accepted viewpoints, a theme that has impelled many artists and repelled much of the public, left behind, puzzling, in the dust.

Lipski, who lives and works in Brooklyn, is showing four large-scale pieces made with the American flag. While he does not consider himself a political artist, the idea of an object so charged with controversy as to raise calls for a constitutional amendment on its behalf was too enticing to ignore.

"Half Conceals/Half Discloses" is an 18-foot flag riddled with scores of neat round holes apparently burned into its nylon fabric. Although implying violence, these holes have a precision hinting at intentional peepholes. Around their edges, remnants of melted nylon remain, their delicate forms repeated by the lacy shadows thrown on the wall behind. In this work, the flag is indeed "disclosed."

The wounds it has sustained focus attention on the hopes and freedoms it symbolizes far more strongly than an unmarred flag could. The flag, which should belong to all Americans, has often been claimed as the exclusive property of "love it or leave it" patriots or even radical hate groups. This is an image of fragility that says as much about the tenuousness of any alliance that forms a nation, as about the frailty of the symbol itself.

In a strangely stirring bit of deja vu, Lipski has installed a monumental X made of two huge flags in the Corcoran's atrium. Longtime Washington residents will remember Ronald Bladen's giant black sculpture, "The X," which stood in the same position in 1968. Made at the Fabric Workshop in Philadelphia from translucent material, Lipski's X is ephemeral by comparison; instead of the aggressive stance of Bladen's, it has the feeling of an airy ceremonial tent. Its spectral stars and stripes play against the solid forms of the gallery's neoclassical columns like a momentary but potent vision. With a theatrical flourish, Lipski reveals the flag both as a symbol and as a physical object. In so doing, he draws us into the realization that the symbol encompasses far more than any single faction would have us believe.

Both of these artists remind us that the physical "art object" is nothing more than a representation of larger ideas. In the early 1980s, Spector began to explore this line of thought with books, which he views as literal containers of ideas. By exposing successive layers of torn pages or by stacking books to create sculptural forms, he has used them for their physicality as opposed to the ideas they make available, contrasting the substantiality of physical presence with the often more enduring substantiality of ideas.

A native of Chicago who now lives in Los Angeles, Spector explores the meanings attached to certain objects by combining them in sculptures that both enhance and contradict those meanings. In his exquisitely morbid "Butter-Roses," a thousand red roses punctuated with rosettes made of butter are frozen in a horizontal, glass-topped freezer. In this coffinlike container, their sensuous color and beauty are preserved for viewing, but they are brittle and stripped of scent. For all practical purposes, they are no more real than a lifelike drawing might be. In the suspended animation of the freezer, they have lost their vitality and with it the basis of their meaning. Spector implies that meaning is dependent on life and its cycles, including decay.

In contrast to Lipski, who prefers to work intuitively and spontaneously, Spector weaves a compelling web of wordplays and allegories into his work. "Hospitalite: Pour Georges Bataille" consists of 11 loaves of bread baked into bedpans and mounted on the wall. The work's title is a pun on hospital and hospitality, and helps to define the work's several possible interpretations. Often the subject of jokes, bedpans are inexorably linked with the pain of physical illness. Yet they also represent the care and hospitality given to a patient too weak to rise from bed.

The shapes of the braided bread in the bedpans recall many things, from feces to babies to prehistoric goddess figurines associated with both birth and death. For many cultures, bread is a sacrament representing a goddess or god and is intended to be shared. It represents the full cycle of growth, nourishment and decay. Spector embraces even the last: This bread, baked last year, is visibly beginning to decay.

Like much idea art, this is not a pleasant piece to look at. But its unappealing looks and the antagonism between the conflicting ideas it embodies are part of its forcefulness. The viewer has only two choices: to puzzle it out or to pass it by and miss out. This is indeed art that transgresses the boundaries of everyday thought, requiring questioning of the roots of one's perceptions. The connections made in this way are unexpected, often humorous, and sometimes exhilarating, when a glimpse of sheer understanding comes through.

Transgressions: Donald Lipski and Buzz Spector, at the Corcoran Gallery of Art, 17th Street and New York Avenue NW, through Feb. 10.