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295 or a priori argument for the proof of God's existence. Yet we find Spinoza in the second proof of his eleventh proposition (Ethics, pt. i) making use of the cosmological argument, and in the scholium which follows writing: "In this last demonstration I wished to prove the existence of God a posteriori, in order that the demonstration might be the more easily understood, and not because the existence of God does not follow a priori from the same grounds." Such slips, however, are exceedingly rare.

The pieces in the Appendix, although not directly relating to Locke, greatly enhance the value of the volume. The first of them, addressed to Thomasius in 1669, is of value as throwing light upon the evolution of Leibnitz's system in his own mind. The sixth is the notable essay on the radical origin of things. The tenth is the curious little essay read by Leibnitz to Spinoza, when he visited the latter at the Hague, in which Leibnitz undertakes to supply what he regards as the missing link in the ontological argument for the being of God, namely, that all perfections are compatible with each other, and hence may exist in one subject, or, in other words, that the idea of the 'All-Perfect' Being contains no inner contradiction, and therefore is the idea of a possible being (a being possible in fact). The twelfth, on the method of distinguishing real from imaginary phenomena, is valuable from its bearing on Leibnitz's epistemological views. The two essays on dynamics, over and above what they have to say about living force and other properly dynamical problems, are particularly instructive on account of what they contain relative to the law of continuity and the nature of matter and substance.

Three full indexes, made by Rev. R. K. Eccles, one to the New Essays, a second to the pieces in the Appendix, and a third to the notes by the translator, still further add to the value of Mr. Langley's book.

Mr. Langley's edition of the New Essays is thus an excellent companion-piece to Professor Campbell Fraser's recent edition of Locke's Essay. It is to be hoped that these books will lead to a renewed study of the great works of Locke and Leibnitz. For these writers have given us classical works in modern philosophy, which the cultured reading public as well as professional students of philosophy have in the past enjoyed, and ought to continue to enjoy. They deal with a wide range of interesting topics, as must be the case with works whose central theme is human knowledge, its origin, nature, certainty, and extent.

This is not the place either to expound or to criticise philosophical speculations which have been more or less before the world for two