The study of sexual physiology, what happens, and why, and how to make it happen better, has been a paying career or a diverting sideline for scientists as far-ranging as Leonardo da Vinci and James Watson. The research has taken place behind the closed doors of laboratories, brothels, MRI centers, pig farms, sex-toy R & D labs, and Alfred Kinsey's attic. The author devoted the past two years to stepping behind those doors. Can a person think herself...