This is the Bible of the Sex Revolution of the 1960s, to such an extent that one cannot say whether this book caused the Sex Revolution or the Sex Revolution led to the creation of this book.This book asked and answered questions that had rarely been addressed and had never been answered before. What happens to the woman during the sexual process? Prior to this book, nobody knew the answer. It can be observed that when a woman becomes sexually aroused, her vagina becomes lubricated through vaginal fluids. Where does this arousal take place? Does it happen just in the clitoris or does it also take place deep within the walls of the vagina? These are questions that Masters and Johnson penetrated.