The primary sources for this work have been Sun Yat-sen’s own works. A considerable number of these were written originally in the English language. Translations of his major Chinese works are more or less fully available in English, German, French, or Spanish. The author’s highly inadequate knowledge of the Chinese written language has led him to depend almost altogether upon translations, but he has sought—in some cases, perhaps, unsuccessfully—to minimize the possibility of misunderstanding or error by checking the translations against one another. Through the assistance of his Chinese friends, he has been able to refer to Sun’s complete works in Chinese and to Chinese books on Sun wherever such reference was imperatively necessary. A list of the Chinese titles thus made available is included in the bibliography. The language difficulty, while an annoyance and a handicap, has not been so considerable as to give the author reason to suppose that his conclusions would have been different in any significant respect had he been able to make free and continuous use of Chinese and Russian sources. The author has thought of the present work as a contribution to political theory rather than to sinology, and has tried to keep the discussion of sinological questions at a minimum. In the transliteration of Chinese words and names he has adhered more or less closely to the Wade system, and has rendered most terms in the _kuo yü_, or national language. Despite this rule, he gives the name of President Sun in its more commonly known Cantonese form, Sun Yat-sen, rather than in the _kuo yü_, Sun I-hsien. In acknowledging assistance and encouragement received, the author must first of all turn to his father, Judge Paul Myron Wentworth Linebarger, Legal Advisor to The National Government of China, counsellor to and biographer of Sun Yat-sen during the latter’s lifetime. Without his patient encouragement and his concrete assistance, this book could neither have been begun nor brought to a conclusion after it was started. The author desires, however, to make it perfectly clear that this work has no relation to the connections of Judge Linebarger with the Chinese Government or with the Nationalist Party. No information coming to the knowledge of Judge Linebarger in the course of his official duties has been here incorporated. Anxiously scrupulous to maintain a completely detached point of view, the author has refrained from communicating with or submitting the book to Chinese Government or Party officials, and writes purely as an American student of China.