whole process may be included in two general classes, Acquisition and Verification. It would be better, in my opinion, not to group the forming of the hypothesis which is an inference, a pure process of inductive reasoning, with the more passive processes of Observation and Classification.
In this able and scholarly work the editor of the Archiv für Geschichte der Philosophie has added to the debt of gratitude which all earnest students of philosophy already owe him. That the philosophy of Leibniz bore an intimate relation to the system of Spinoza was felt, as Professor Stein points out, even in Leibniz's own lifetime; and ever since the controversy between Mendelssohn and Jacobi as to Lessing's views, the precise relation of the two philosophers has been a subject of dispute. No satisfactory conclusion, our author contends, is possible, so long as the 'speculative-constructive' method is employed: and therefore he has had recourse to the 'literary-historical' method, now generally recognized to be the true one. The completion of Gerhardt's edition of Leibniz's philosophical works, and the discovery, in the Leibniz archive at Hanover, of nineteen new pieces (now published in this volume as an Appendix), have enabled the author not only to show that the association of Leibniz and Spinoza was for a short time of a close and intimate kind, but to throw light upon the mental development of the former in all its stages.
Under Dr. Stein's enlightened guidance we learn that up to the age of twenty-five, Leibniz (b. 1646) was on the whole a follower of Hobbes, or rather he adopted the mechanical conception of Nature in the form set forth by Hobbes, though he never ceased to believe that it was capable of being reconciled with his early religious conceptions. From 1672 to 1695 his attitude towards Descartes is one of doubt. Even in 1670, though he accepts the Cartesian doctrine that the essence of matter consists in extension, he is sceptical of its conception of force; and in 1672 he raises the difficulty that, if matter is pure extension, a body cannot alter in size without losing its reality. But it was only about 1675 that he became profoundly dissatisfied with Cartesianism. In this dissatisfaction he was strengthened by his intercourse in Paris with Tschirnhausen, from whom he learned that Spinoza like himself had revolted from Descartes, and in particular that he
