Christian Wolff was born at Breslau in 1679, studied theology at Jena, and in addition mathematics and philosophy, habilitated at Leipsic in 1703, and obtained, through the instrumentality of Leibnitz, a professorship of mathematics at Halle, in 1706. His lectures, which soon extended themselves over all philosophical disciplines, met with great success. This popularity, as well as the rationalistic tendency of his thinking, aroused the disfavor of the pietists, Francke and Lange, who succeeded, in 1723, in securing from King Frederick William I. his removal from his chair and his expulsion from the kingdom. Finding a refuge in Marburg, he was called back to Halle by Frederick the Great a short time after the latter's ascension of the throne. Here he taught and wrote zealously until his death in 1754. In his lectures, as well as in half of his writings,[1] he followed the example of Thomasius in using the German language, which he prepared in a most praiseworthy manner for the expression of philosophical ideas and furnished with a large part of the technical terms current to-day. Thus the terms _Verhältniss_ (relation), _Vorstellung_ (representation, idea), _Bewusstsein_ (consciousness), _stetig (continuus)_, come from Wolff, as well as the distinction between _Kraft_ (power) and _Vermögen_ (faculty), and between _Grund_ (ground) and _Ursache_ (cause),[2] Another great service consisted in the reduction of the philosophy of Leibnitz to a systematic form, by which he secured a dissemination for it which otherwise it would scarcely have obtained. But he did not possess sufficient originality to contribute anything remarkable of his own, and it showed little self-knowledge when he became indignant at the designation Leibnitzio-Wolffian philosophy, which was first used by his pupil, Bilfinger. The alterations which he made in the doctrines of Leibnitz are far from being improvements, and the parts which he rejected are just the most characteristic and thoughtful of all. Such at least is the opinion of thinkers to-day, though this mutilation and leveling down of the most daring of Leibnitz's hypotheses was perhaps entirely advantageous for Wolff's impression on his contemporaries; what appeared questionable to him would no doubt have repelled them also. Leibnitz's two leading ideas, the theory of monads and the pre-established harmony, were most of all affected by this process of toning down. Wolff weakens the former by attributing a representative power only to actual souls, which are capable of consciousness, although he holds that bodies are compounded of simple beings and that the latter are endowed with (a not further defined) force. He limits the application of the pre-established harmony to the relation of body and soul, which to Leibnitz was only a case especially favorable for the illustration of the hypothesis. By such trifling the real meaning of both these ideas is sacrificed and their bloom rubbed off.--While depth