(1) There has been omitted from this edition a long, tiresome chapter contained in the original edition, entitled "On the Power of the Mind to master disordered Feelings by sheer Determination. As Set forth by Immanuel Kant in a letter to Hufeland," but which chapter had very little to say about "the power of the mind," but very much indeed about Hygiene, Dietetics, Sleep, Care of Oneself in Old Age, Hypochondria, Work, Exercise, Eating and Drinking, Illness, etc., etc., from the point of view of the aged German metaphysician, which while interesting enough in itself, and to some people, was manifestly out of place in a book treating upon the development of Mental Faculties by the Will, etc. We think that Mr. Leland's admirers will find no fault with this omission. (2) The word "Suggestion" has been substituted for the word "Hypnotism" in several places in the original text, where the former word was manifestly proper according to the present views of psychologists, which views were not so clearly defined when the book was written. (3) The chapter headings of the original book have been shortened and simplified in accordance with the American form. (4) The title "The Mystic Will" has been substituted in place of that used in the original edition, which was "Have You a Strong Will?" This change was made for the reason that the original title did not give one the correct idea of the nature of the book, but rather conveyed the idea of an inquiry regarding the "iron-will," etc., which the author evidently did not intend. The use of the Will, as taught in the book by Mr. Leland, is not along the lines of "the iron-will," but is rather in the nature of the employment of a mystic, mysterious, and almost weird power of the Human Will, and the title of the present edition is thought to more correctly represent the nature of the book, and the author's own idea, than the inquiry embodied in the title of the original edition. (5) Several unimportant footnotes, references to other books, etc., have been omitted after careful consideration. (Those who would wish to read the book in its original English edition will be able to procure it from the English publisher, Mr. Philip Wellby, 6 Henrietta street, Covent Garden, London, W. C, England.) To the few readers of this book who are not familiar with the author, Mr. Charles G. Leland, it may be said that this gifted man was an American by birth, but who lived in Europe for many years before his death. He died March 20, 1903, at Florence, Italy, at the ripe age of 79 years, active until the last and leaving unpublished manuscripts, some not completed. He lived up to his ideas and profited by them. His writings are spread over a period of nearly, or fully, fifty years, and his range of subjects was remarkable in its variety, style, and treatment.