This book gives the reader a simple, intelligible description of what is known about rejuvenation. No one can afford to go on living without giving serious thought to this subject. The observations of the author are based on a study of Steinach literature, punctuated with discussions he had with Steinach himself, with Dr. Peter Schmidt, his chief German interpreter, with various students of endocrinology in the United States and by personal investigations of the cases of many people who were successfully "Steinached."