Even the women who wept when Valentino died might find it hard to grasp what it means to be a raver. Today the girls who follow the pop groups start young-and once started there is no stopping them. They come from every kind of background. The only things they share in common are their youth and their idols -and the fact that they are part of a world their parents know nothing about, a world with its own jargon, its own morality, a world where the social pattern their parents thought entirely natural has been turned on its head and the girls have become the hunters, the boys the hunted.