Victorian men placed fig leaves over those parts of classical statues they didn't want their wives and children to see. Yet it's easy for someone looking at those statues today to assume that the leaves play some part in the Roman and Greek concepts of physical beauty.

A fig leaf may be the most blatant breach of an artist's original inspiration you'll encounter in a museum, but it's not likely to be the only one. Other more subtle transgressions are displayed in nearly every gallery and museum in the country—but unmasking them takes more than just a discerning eye. For instance, did the 17th-century painter see the world as quiet and subdued, or have his bright colors been muted by a 19th-century varnish? Did the classical sculptor intend his work to have an even, green patina, or has the Renaissance infatuation with antiquity allowed this corrosion to hide his varying shades of burnished bronze? Did Leonardo conceive the face of the Christ of “The Last Supper” as speaking, or silent, as his overpainters would have it?

“Modern conservators really make us think about objects, says Carol Faill, administrator of college collections at Franklin & Marshall College. “There's been a consciousness raising about objects' own integrity.” Art and science are being used together as never before to gain an understanding of the physical and chemical properties of materials and their role in the fine arts.