Don’t touch!” Just about the first thing one learns about visiting art museums is that anything but visual contact with the works on display is absolutely forbidden. There are many variations on how this restriction is announced, ranging from polite requests, such as the discreet “Please do not touch the works of art,” to earnest, detailed explanations of the harmful effects of the invisible salts and oils present on even the cleanest of hands on even the sturdiest of art materials. We are frequently told—and just about all of us who care about art are convinced—that the long-term preservation of paintings, sculptures, and works on paper for the enjoyment and instruction of everyone depends upon our exerting restraint and keeping our hands off. It’s an example of voluntarily subsuming personal wishes for the greater good that would gladden the heart of Isaiah Berlin. Yet we also know that in the past—and even in the present—this kind of disciplined abstemiousness did not necessarily apply to many of the “users” of the works in question or to the collectors who acquired them.

We’re all familiar with devotional works of art that have been ritually touched by worshippers. Think of the worn toes of Arnolfo da Cambio’s bronze statue of Saint Peter in Rome, eroded by the lips of medieval pilgrims, or of the blurred icons in Russian churches, their details lost to the repeated kisses of the faithful; in present-day Russia, where the practice still continues, churches with a rich