The world of a classical musician is always a difficult one. It calls for an obsessive dedication to the hardest of crafts and then, when that is mastered, a further period of toil to find an individual signature. But such a narrative ignores the artiste’s personal strife in a social setting that is often hostile to his or her ambitions. That is what makes Deepa Ganesh’s A Life in Three Octaves, a biography of Gangubai Hangal, especially moving. The uninitiated may ask: who was