It had the two main ingredients that most best sellers of it's time had--sex and violence. Other best sellers back then followed the same formula- VALLEY OF THE DOLLS, by Jacqueline Susanne, and anything by Harold Robbins, to name just two. But I'll be damned if I know why it was such a HUGE seller. As I've said before, it certainly wasn't great literature. Other best selling writers of the time, such as Herman Wouk and Philip Roth, wrote much better books IMO, but never approached the sales of GF. Go figure.