‘What grace coupled with what brutality!’ was Jean Cocteau’s verdict after he first encountered Vaslav Nijinsky – an exclamation which seems an apt epitome of a man whose dancing and choreography revolutionised ballet and created a legend that still smoulders today, nearly a century after he abandoned his art and descended into a black mental and emotional hole from which he never fully emerged.

Although drawing solely on secondary sources (the spadework, including extensive interviews with Nijinsky’s widow, friends and witnesses, was done by Richard Buckle for his 1971 biography), Lucy Moore’s new study of this often inscrutable figure is highly intelligent, lucidly presented and consistently absorbing. Sometimes her first-person speculations are obtrusive and the flights of fancy at the book’s opening and closing seem misjudged, but she tells a remarkable story with great flair, as sensitive to psychological complexities as she is judicious in her aesthetic judgements.

It can’t have been an easy task. Even before he lost his reason, Nijinsky was pathologically shy and feral – today he would doubtless be diagnosed with Asperger’s. ‘I do not know how to be polite because I do not want to be,’ he muttered. Address him in the wrong way,