Adrien Sixte had made two contributions to philosophy. The first was a negative analysis of what Herbert Spencer calls the Unknowable. “Many excellent minds,” the author assures us, “catch a glimpse of the probable reconciliation of science and religion on this ground of the Unknowable. For M. Sixte it is a last illusion which he is hot to destroy with an energy of argument that has not been equalled since Kant.” “M. Sixte’s second title to honor as a psychologist consists in a quite new and ingenious development of the animal origin of human sensibility.... He undertook for the genesis of types of thought the work that Darwin essayed for the forms of life. Applying the laws of evolution to all the facts that make up the human heart, he thought to show that our most exquisite sensibilities, our most delicate moral discriminations, as well as our most shameful degradations, are the final development, the ultimate metamorphosis of very simple instincts, themselves transformations of the properties of the primitive cell: in such wise that the moral universe exactly reproduces the physical, and that the former is only the consciousness, now painful, now ecstatic, of the latter.” We owe to M. Sixte some phrases that translate with extreme energy this conviction that all is necessitated in the soul--even the illusion that the soul is free. “Every act,” he writes, “is but an addition. To say that it is free, is to say that there is in a sum more than there is in the elements added. This is as absurd in psychology as in arithmetic.” And elsewhere he put it thus: “If we knew truly the relative position of all the phenomena which constitute the actual universe, we could at this moment with a certainty equal to that of the astronomers, tell the day, the hour, the minute at which, say, England will evacuate India, when Europe will have burned its last lump of coal, when such a criminal, still to be born, will assassinate his father, when such a poem, yet to be conceived, will be composed. The future is contained in the present as all the properties of a triangle are contained in its definition.” The provenance of this type of thought is obvious enough to the experienced reader. Our author has in an ingenious way translated his Spinoza into the language of contemporary science. Let us merely catch up a note or two that will render our Spinozist’s attitude toward common morality, and his understanding of the master’s doctrine of emancipation through science.