The big new art history “Art Since 1900” is “formidably high-brow.” It “is spectacular, gargantuan and painstakingly conceived so that it can be read in a number of ways. The authors have selected what they consider to be a defining event for every year and written essays about each one. But within those essays are signposts to other entries, so that if you were interested in a particular strand of thought, you could follow it throughout the century. The possibilities of this are endless and it’s not long before you realise that the book could be not 700 but 7,000 pages long, depending on the historical maps you choose to draw up for yourself.”