Masters and Johnson were a pioneering team in the field of human sexuality, both in the domains of research and therapy. William Howell Masters, a gynecologist, was born in Cleveland, Ohio in 1915. Virginia Eshelman Johnson, a psychologist, was born in Springfield, Montana in 1925. To fully appreciate their contribution, it is necessary to see their work in historic context. In 1948, Alfred C. Kinsey and his co-workers, responding to a request by female students at Indiana University for more information on human sexual behavior, published the book Sexual Behavior in the Human Male. They followed this five years later with Sexual Behavior in the Human Female. These books began a revolution in social awareness of and public attention given to human sexuality. At the time, public morality severely restricted open discussion of sexuality as a human characteristic, and specific sexual practices, especially sexual behaviors that did not lead to procreation. Kinsey's books, which among other things reported findings on the frequency of various sexual practices including homosexuality, caused a furor. Some people felt that the study of sexual behavior would undermine the family structure and damage American society. It was in this climate - one of incipient efforts to break through the denial of human sexuality and considerable resistance to these efforts - that Masters and Johnson began their work. Their primary contribution has been to help define sexuality as a healthy human trait and the experience of great pleasure and deep intimacy during sex as socially acceptable goals. As a physician interested in the nature of sexuality and the sexual experience, William Masters wanted to conduct research that would lead to an objective understanding of these topics. In 1957, he hired Virgina Johnson as a research assistant to begin this research issue. Together they developed polygraph-like instruments that were designed to measure human sexua...