Since they began opening their doors to the public toward the end of the eighteenth century, art museums have been repositories of superior art. They have attempted to separate the wheat from the chaff, the permanent and profound from the inferior and transient. They display objects judged by the eye of history to be the most important of the civilizations that produced them. They have been places where visitors view art of the highest order, sanctuaries that offer enlightenment, inspiration, wisdom, and solace, far from the hurly burly of daily life.

But beginning in the 1960s, the idea of museums as sentinels of excellence, education, and expertise was challenged as antiquated, elitist, and just pl ...