Marcel Duchamp suggested the name “mobiles” for Alexander Calder’s primary contribution to art history and it stuck. Jed Perl’s Calder biography of the man behind the mobiles deserves to be called magisterial. The Conquest of Time is learned and comprehensive, written in good English rather than turgid academic prose and placing its subject in the context. The son and grandson of sculptors, Calder went to 1920s Paris where he was in direct touch with modern artists. Like many of them, his work drew from a sense of dynamism in a world where nothing stood still for long. To Calder, his three-dimensional mobiles suggested a fourth dimension: time as marked by motion. Calder’s were artworks of uncertainty, “their relations and juxtapositions ever changing.” Volume one in Perl’s planned monumental set on Calder’s life includes hundreds of photographs of the man and his work.