The story in this book is so gripping and fascinating that it is remarkable that it has never been told in this way before. It is probably just as well, for it is hard to imagine another account showing such fluency, wit and attention to detail as Alexander Waugh’s. Most literate people have heard of Ludwig Wittgenstein, the Austrian philosopher who made a substantial career at Cambridge under the patronage of Bertrand Russell, and whose Tractatus is considered one of the finest works of twentieth-century thought. Others will know of his brother, Paul, a gifted concert pianist who lost his right arm in 1914 fighting for Austria against the Russians and who then used some of his considerable wealth to commission the most famous composers of the day (including Prokofiev, Britten and, most important, Ravel) to write works purely for the left hand. Yet these were only the tip of the Wittgenstein iceberg. A big family, built on manufacturing wealth, living in palatial style in Vienna, visited by personal tragedy, torn apart by two wars, in the second of which their Jewish ancestry made life exceptionally complicated: it is dramatic stuff. Waugh avoids triteness and vulgarity, but that ought not to stop him selling the film rights for a fortune.

The head of the family was Karl Wittgenstein, born into a respectable middle-class family in the 1840s. He failed at school and ran away from home in 1865, barely seventeen, and seemed to have disappeared: he was in fact on his way to New York, where he piloted a canal