I have made it no part of my plan to dwell on details. The interest and significance of the history of socialism will be found, not in its details and accidents, but in the development of its cardinal principles, which I have endeavoured to trace. Readers desirous of detail must be referred to the writings of the various socialists, or to works that treat of special phases of the movement. Yet I hope that the statement of the leading theories is sufficiently clear and adequate to enable the reader to form his own judgment of the highly controversial matters involved in the history of socialism. I may add that in every case my account is drawn from an extensive study of the sources. These sources I have given both in the text and in footnotes. For the more recent development of the subject, however, the material is derived from such a multitude of books, pamphlets, periodicals, and journals, as well as from personal inquiry and observation, that it has not been found practicable to indicate them. But the purely historical part of such a work is far from being the most difficult. The real difficulty begins when we attempt to form a clear conception of the meaning and significance of the socialistic movement, to indicate its place in history, and the issues to which it is tending. In the concluding chapters I have made such an attempt. The good reader who takes the trouble to go so far through my book can accept my contribution to a hard problem for what it is worth. He may at least feel assured that it is no hasty and ill-considered effort which is placed before him. The present volume grew out of the articles on socialism published in the ninth edition of the _Encyclopædia Britannica_. The views advocated there were first set forth in my _Inquiry into Socialism_, published in 1887. In this edition of the _History_ they have in some points received such expansion and modification as time and repeated, self-criticism have suggested. I beg particularly to invite the attention of the reader to the last two chapters, in which the present position of socialism and its relation to some contemporary questions, such as those of Empire, are set forth. To all thoughtful and discerning men it should now be clear that the solution of the social question is the great task which has been laid upon the present epoch in the history of the world. Socialism grew to be a very important question during the nineteenth century; in all probability it will be the supreme question of the twentieth. No higher felicity can befall any man than to have thrown a real light on the greatest problem of his time; and to have utterly failed is no disgrace. In such a cause it is an honour even to have done efficient work as a navvy or hodman.