In preparing this book, I relied on many sources -- medical journals, papers presented at scientific meetings, reference books, newspaper accounts, and interviews that I myself conducted. The sources consulted have been cited whenever possible. I am particularly indebted to my fellow medical and science writers, and to my colleagues in the Kennedy Interfaculty Program in Medical Ethics at Harvard University. While I am grateful to all who helped, I alone am responsible for the book's point of view and any errors it contains.
John Langone Hingham, Massachusetts January, 1977