“‘The right function of every museum,’ wrote John Ruskin, the influential 19th-century art and social critic, ‘is the manifestation of what is lovely in the life of nature, and heroic in the life of men.’ Museums of the 21st century have moved on a bit. … They are also ‘destination’ enterprises, with permanent collections and special exhibitions, cafes and shops trying to attract as many visitors as possible in an age of global tourism. … As leading museums compete for crowd-drawing exhibits, and try to balance commercial interests and cultural diversity, visitors are bearing a rising proportion of the cost.”