Raphael, Madonna del cardellino (1507)

As objects, works of the visual arts not only must survive, they also need to be seen, touched, entered into, and, in every respect, experienced in their physical dimension. The instant we gaze on a painting, examine a sculpture, or enter an architectural space, the issue of conservation arises, posing a multitude of questions, whether we are aware of them or not. How much of what is before us is original? To what degree of later manipulation has the object been subjected? Has there been deterioration in the constituent materials, and, if so, was this due to natural or man-made causes? Are we looking at a fragment or at the whole? The list goes on. Conservation, in a very real sense, is the arbiter of our artistic patrimony—of its substance and our understanding of it.

Indeed, conservation problems are just one of the many factors affecting our perception of virtually every art object. Or, put another way, any experience of an art object is perforce conditioned by a multitude of variables, some of which are self-evident: light (its quality and intensity), perspective (position and viewing angle), proximity (or distance), and other environmental factors. Conservation is yet another factor, and it is often the most critical. The reason is simple: unlike the literary and musical arts, the visual arts are defined by substantive, three-dimensional properties—works of art exist as objects, physical