When artists choose to work in collage or assemblage. they open a door and let the world into their work. The problem then becomes one of keeping the world at bay, of sustaining the work of art so that real-life objects and references play their assigned roles and no others. Much of the interest in collage derives from this now-symbiotic, now-antagonistic pull between life and art.

Imagine, then, how complicated things become when art invades art, not just in the form of allusion or quotation but as a fusion of a preexistent work with a new one. This is one of the issues raised by the work of