NEW BOOKS. 265 stituted as we are, some sense organs only are muscular, and if it is the fact of muscularity whereby we have apprehension of extension, it be- comes a necessity for us to have those sensations ' in ' space. We are so ordered, through the mobility of our hands, eyes, etc., as to have those sensations so. Here is the explanation of this necessity because of our organic constitution. . . . "We make, we determine space ; we come to know it by way of construction not of a priori construction, not of spontaneity of thought, as Kant said, but by conscious bodily exertion, not limited by occasions of passive sense-impressions [i.e., not had merely by experience from without, but by activity of ours put forth, springing from within]. And this is because we are what we are. We are thrown back on our original constitution. Hence it is that the science of Space is different from the inductive sciences of nature ; hence it is that mathematics is a demonstrative science. The explanation applies to all sciences in so far as they are demonstrative to arithmetic and physics, e.g., as well as to geometry for all are, to that extent, con- cerned with matter as apprehended by activity, by construction ; and herein lies their ' necessity '. Other sciences we form piecemeal from experience." This being so, Robertson is willing to admit, with Kant, that Space, although not itself a simple experience, is a " form " : all simple sensa- tions come to have a reference to it. But he denies that it is a "pure intuition ". His reason for this is, that it can be psychologically ex- plained. Furthermore, he maintains, as against Kant, that space is no universal form of external sensation. True, " every sensation does come to have some kind of spatial reference more or less". But "there is all the difference in the world of DEGREE. For that difference of degree we must account in detail, and this puts a check on our agreeing with Kant's superficial assertion, that space is form for all sensations alike. Do the notes in the scale of an octave or in a chord appear to us spread out in space like the colour-spectrum ? It is true that we should hear them as 'in space,' yet the spatial order is very different." Thus does Eobertson attempt to mediate between experiential psy- chology and Kantian teaching. But he attempts also to conserve what is good in discredited distinctions nearer home as, for example, in the distinction between the primary and secondary qualities of Matter. And, in dealing with Knowledge and Belief, he insists strongly that, while from one point of view knowledge is requisite for belief, in another aspect of it belief is presupposed in knowledge. Take the case of our knowledge of external reality. This is impossible without the tacit assumption of the uniformity of nature. But this tacit assumption is simply belief. There is a lack here of that precision which usually characterizes Robertson. The distinction should be drawn between "belief" and "faith," and the latter term restricted to such primitive trust, or native confidence, as we place in postulates. Were this done a great deal of dispute mainly verbal, after all would be at once got rid of. It is very satisfactory that we have in this book so much about Kant of whom Robertson made a special study, extending over many years. It is a pity that we have not a similarly full account of Leibniz, to whose doctrine of Monads, as expressing the ultimate philosophical analysis of the universe, Robertson gave his adherence. We should have liked also to hear more about Spinoza, whose Epistemology is one of the finest things that the Cartesian School ever did, and whose psychological ^analysis of the Emotions in Part iii. of the Ethica scarcely finds a parallel till we come to Dr. Thomas Brown and Professor Bain. But
