For 60 years, the celebrated photo agency Magnum has attracted many of the world's best photographers. Fifty-five of these artists were asked to select and comment on photos by one or more of their colleagues; the results in Magnum Magnum (Thames & Hudson) are as illuminating as they are visually compelling. So Susan Meiselas gives us Robert Capa's lesser-known shots of the Spanish civil war; Elliott Erwitt offers Eve Arnold's haunting portrait of Richard Burton and Elizabeth Taylor; and Alex Webb informs us that Larry Towell (whose contributions include a startling picture of a cherubic baby asleep among vats of pickles) carries a business card that reads HUMAN BEING. Magnum Magnum persuades us that all of these artists, whose work is a collective testament to the complexity of human experience, could identify themselves as members of that same profession.