As a consequence of this interest, I was asked by the _Cosmopolitan_ to write another article, which appeared in the issue of February, 1911. The present volume is made up from these two articles, with the addition of some notes and comments, and some portions of articles contributed to the _Physical Culture_ magazine, of the editorial staff of which I am a member. It was my intention at first to work this matter into a connected whole, but upon rereading the articles I decided that it would be better to publish them as they stood. The journalistic style has its advantages; and repetitions may perhaps be pardoned in the case of a topic which is so new to almost every one. I have reproduced in the book several photographs of myself which appeared in the magazine articles. Ordinarily one does not print his picture in his own books; but when it comes to fasting there are many "doubting Thomases," and we are told that "seeing is believing." The two photographs of myself which appear as a frontispiece afford evidence of a really extraordinary physical recuperation; and the reader has my word for it that there was nothing in my way of life to account for it, except three fasts, of a total of thirty days. There is one other matter to be referred to. Several years ago I published a book entitled "Good Health," written in collaboration with a friend. I could not express my own views fully in that book, and on certain points where I differed with my collaborator, I have come since to differ still more. The book contains a great deal of useful information; but later experience has convinced me that its views on the all-important subject of diet are erroneous. My present opinions I have given in this book. I am not saying this to apologize for an inconsistency, but to record a growth. In those days I believed something, because other people told me; to-day I know something else, because I have tried it upon myself.