There’s a new “revised version of ‘Janson’s History of Art,’ a doorstopper first published in 1962 that has been a classroom hit ever since Horst Woldemar Janson wrote it while working at New York University. For a generation of baby boomers, it defined what was what and who was who in art. But in recent years it has lost its perch as the best-selling art survey and has been criticized for becoming a scholarly chestnut. So its publisher recruited six scholars from around the country and told them to rewrite as much as they wanted, to cast a critical eye on every reproduction, chapter heading and sacred cow.”