When he died, at 57, Serge Pavlovich Diaghilev (1872-1929) was many things: the most celebrated of Russian émigrés; the impresario of the Ballets Russes, the world’s most famous ballet company; a pivotal figure in the recent histories of opera, stage design, visual arts, classical music, as well as theatrical dance; the hub of successive schools of artistic modernism; the man who had taken ballet from state patronage into the world of commercial sponsors; the most celebrated homosexual since Oscar Wilde.