Peter Schjeldahl pays his first-ever visit to the Barnes Collection and weighs in on discussions now determining its fate. “Altering so much as a molecule of one of the greatest art installations I have ever seen would be an aesthetic crime. It would also give hosts of my fellow art lovers access to treasures that they might otherwise never see. And it’s not as if aesthetic crimes don’t happen all the time. Life goes on. But something extraordinary would be lost in the event.”