His doctrines have provided the theories upon which the Nationalist revolution was based; they form the extra-juridical constitution of the National Government of China. When the forces hostile to Sun Yat-sen and his followers are considered, it is amazing that his ideas and ideals should have survived. An empire established with the aid of Japanese arms, and still under Japanese hegemony, controls Manchuria; parts of north China are ruled by a bastard government, born of a compromise between enemies; a largely unrecognized but powerful Soviet Republic exists in outer Mongolia; the lamaist oligarchy goes on in Tibet; and somewhere, in central and western China, a Soviet group, not quite a government but more than a conspiracy, is fighting for existence. It is quite probable that nowhere else in the world can there be found a greater variety of principles, each scheme of principles fostered by an armed organization struggling with its rivals. In this chaos the National Government has made the most effective bid for authority and the greatest effort for the reëstablishment of order; through it the principles of Sun Yat-sen rule the political life of a population greater than that of the United States or of the Soviet Union. It is difficult to evaluate the importance of political doctrines. Even if _The Three Principles_ is judged by the extent of the population which its followers control, it has achieved greater results in practical politics in fifteen years than has Marxism in ninety. Such a criterion may well be disputed, but, whatever the test, it cannot be denied that the thought of Sun Yat-sen has played a major part in the political development of his native land. It may continue into the indefinitely remote future, or may succumb to the perils that surround its advocates; in any case, these doctrines have been taught long enough and broadly enough to make an impress on the age, and have been so significant in political and cultural history that they can never sink into complete obscurity. What are these doctrines? Sun Yat-sen was so voluminous a writer that it would be impossible for his followers to digest and codify all his writings into one neat and coherent handbook; he himself did not provide one. Before printing became common, there was a certain automatic process of condensation which preserved the important utterances of great men, and let their trivial sayings perish. Sun, however, must have realized that he was leaving a vast legacy of materials which are not altogether coherent or consistent with one another. Certain of his works were naturally more important than others, but, to make the choice definitive, he himself indicated four sources which his followers might draw upon for a definitive statement of his views.(4)