When she died in November 1997, a quarter of a million Parisians came on to the streets and thousands stood for hours at her grave, chanting "Dis, quand reviendras-tu?" ("Tell me, when will you return?")

Every leaf I turn in pursuit of her, every conversation, produces a breath-stopping secret. A close friend was the child of a Nazi collaborator. Her sister lived in Israel. Generous and tactile, she would not let anyone touch two of her possessions — her dark glasses and her piano. "A phallic symbol," sighs my analyst.

I don't expect to get to the bottom of Barbara in a one-off radio documentary, but that doesn't mean I have to stop. The songs are endlessly appealing, both as music-lyrical constructs and for their psychological ambivalence. I have listened to the complete recordings and am on to the online pirates. There is always another level of meaning, an alternate suggestive inflection.

When Barbara sings "Dis" to an absent lover, she is not just asking when he'll return. She is showing she can get by without him. Alone is not that bad. There are other consolations. There is always music, that deathless hope.