It is interesting to note how the philosophic spirit, the instinct for unity and generality, showed itself even in the least of Leibniz's tasks. The Duke of Brunswick imposed upon Leibniz the task of drawing up a genealogical table of his House. Under Leibniz's hands this expanded into a history of the House, and this in turn was the centre of an important study of the German Empire. It was impossible that the philosopher, according to whom every real being reflected the whole of the universe from its point of view, should have been able to treat even a slight phase of local history without regarding it in its relations to the history of the world. Similarly some mining operations in the Harz Mountains called the attention of Leibniz to geological matters. The result was a treatise called "Protogäa," in which Leibniz gave a history of the development of the earth. Not content with seeing in a Brunswick mountain an epitome of the world's physical formation, it was his intention to make this an introduction to his political history as a sort of geographical background and foundation. It is interesting to note that the historical studies of Leibniz took him on a three years' journey, from 1687 to 1690, through the various courts of Europe,--a fact which not only had considerable influence upon Leibniz himself, but which enabled him to give stimulus to scientific development in more ways and places than one. His philosophical career as an author begins for the most part with his return to Hanover in 1690. This lies outside of the scope of the present chapter, but here is a convenient place to call attention to the fact that for Leibniz the multitude of his other duties was so great that his philosophical work was the work "of odd moments." There is no systematic exposition; there are a vast number of letters, of essays, of abstracts and memoranda published in various scientific journals. His philosophy bears not only in form, but in substance, traces of its haphazard and desultory origin. Another point of interest in this connection is the degree to which, in form, at least, his philosophical writings bear the impress of his cosmopolitan life. Leibniz had seen too much of the world, too much of courts, for his thoughts to take the rigid and unbending form of geometrical exposition suited to the lonely student of the Hague. Nor was the regular progression and elucidation of ideas adapted to the later Germans, almost without exception university professors, suited to the man of affairs. There is everywhere in Leibniz the attempt to adapt his modes of statement, not only to the terminology, but even to the ideas, of the one to whom they are addressed. There is the desire to magnify points of agreement, to minimize disagreements, characteristic of the courtier and the diplomat. His comprehensiveness is not only a comprehensiveness of thought, but of ways of exposition, due very largely, we must think, to his cosmopolitan education. The