Artworks are rented out by the museums that own them. Exhibitions with corporate pedigrees or board members' business interests at heart are common. Museum professionals curate gallery shows and gallerists double as curators. The line between nonprofit museums and the commerce of art has never been blurrier, art critic Christopher Knight writes, and it is allowing a relentless commercialism. Nonprofit status "was invented more than a century ago to foster diversity of independent thought, free from the narrow economic demands of business or the ideological commands of government. Today that independence is being corrupted,” he says.