For the sections on Tom Starzl and transplantation immunology, I relied on many sources. Much of the work originally appeared as an article in The New York Times Magazine (“The Drug That Works in Pittsburgh,” September 30, 1990), and though I was generally required by the University of Pittsburgh to be accompanied by a member of the staff when speaking with patients on my visits to the medical center, Starzl and all members of the staff were consistently open and receptive. I owe thanks to Cheryl Ackerman, Barbara Banner, Richard Cohen, Benjamin Eidelman, Anthony Demitris, Ashok Jain, Yukio Murase, Jerry McCauley, Mike Nalesnick, Camillo Ricordi, Raman Venkataramanan, and Vijay Warty. I also am indebted to Starzl’s remarkable secretary, Terry Mangan.