years for its completion. His first volume was preliminary, and contained an exposition of his method, under the title of "First Principles." Then followed two volumes of the "Principles of Biology," which was succeeded by two volumes of the "Principles of Psychology." This work is just finished, and takes him half through his undertaking. He has now before him the subject of Sociology, which he proposes to treat in three volumes of the "Principles of Sociology," to be commenced this winter. His Philosophical Series will be completed by two additional volumes of the "Principles of Morality," as deduced from the whole system of facts and principles established in the preceding works.
At this stage of his enterprise, Mr. Spencer encounters certain difficulties which have to be met by what we may call side-undertakings—works which have an important bearing upon the subject of Sociology, but are not properly parts of his philosophical system. The articles that are appearing in The Popular Science Monthly, and which, when completed, will form a volume of the International Scientific Series, are designed to explain the nature, scope, and claims of Social Science. Such are the general doubt and misapprehension regarding this subject, that Mr. Spencer was induced to pause for a little at this stage of his labors, and present some considerations of the method and subject-matter of Sociology which are greatly needed by the public, and which do not properly fall within the course of his regular exposition. It is important to make this explanation, as the papers we have published have been supposed, by some, to be a part of his long-expected "Principles of Sociology."
Another of the difficulties of his undertaking was foreseen by Mr. Spencer several years ago, and has led to a separate work, which, though indispensable to the main plan, is nevertheless of independent value, and of great public importance. As the scientific character of his philosophy is fundamentally inductive, the first work in each department is the collection of data on which inductions are to rest. The data of Biology are accessible in treatises on Natural History, where they can be obtained in a digested and authentic form, while any defects may be supplied by special investigations. The data of Psychology are also available in scientific works upon that subject, and the conditions for extending and verifying them can be commanded anywhere. But, as respects its data, Sociology is very different from these sciences. Dealing with the phenomena manifested by diverse races and communities of men; dealing with the development of society, which is a problem of history; dealing with those facts of the social state which illustrate its natural laws; and dealing, moreover, by a scientific method, with a great subject which has hitherto been regarded as not amenable to that method, the difficulty of gathering the indispensable and pertinent facts for such an inquiry was formidable. History has occupied itself with quite other things than the record of such facts. Travellers fill their pages with chaffy gossip and egotistical narrative, and give but little attention to the social facts which it is most desirable-to know. Their observations are careless, and their statements loose and often untrustworthy. Nobody has taken pains to collect and sift from the vast mass of historical rubbish and the bulky litter of travellers the few and scattered statements which throw-light upon the laws of social life. Before there can be a science of Sociology presenting the generalizations of sociaL phenomena, there must first be an accumulation and a classification of its-data. What these are it is important to understand, and, in a remarkable passage of a review article published