WHAT IS TRANSCENDENTAL PHYSICS? 317 



derived from experience, "by means of the causal principle existing 

 a priori in our intellect." Kant held, on the contrary, thai our idea 

 of space is not a mere conception, but a pure intuition ; that it belongs 

 to the faculty of sense ; that it is in fact one of the necessary condi- 

 tions of sensation, without which experience itself is impossible ; and, 

 finally, that the " causal principle " originates in the higher faculty of 

 the understanding, to which sense delivers up its presentations ready 

 cast in the mold of space. In the philosophy of Kant, therefore, the 

 " causal principle " has nothing to do with the origin of the idea of 

 space, which emerges before sensation rises to the sphere of that prin- 

 ciple. Kant, among his endless subtilties, distinguished indeed be- 

 tween the form of the intuition and the formal intuition, in which 

 space is represented as an object, and with which unity of representa- 

 tion is given through the understanding ; but the determination of 

 this unity, he taught, is contained a priori in the intuition, not devel- 

 oped a posteriori, gradually or otherwise. As a formal intuition, space, 

 like every other sensuous intuition, Kant maintained, is subject to the 

 categories of the understanding, causality included, but the subjection, 

 besides extending to all sensuous intuitions alike, is a priori, and as 

 such incapable of expansion or contraction by experience, the possi- 

 bility of which presupposes it. In the Kantian theory causality has 

 nothing special to do in any mode with the idea of space in any aspect. 

 In common with the other categories, it is simply presupposed in 

 every intuition of sense, that of space with the rest. It lies at the 

 bottom of the possibility of experience in general. Moreover, an a 

 priori principle, as already intimated, is not a germ susceptible of 

 growth, but rather a die, which for ever impresses the same form. A 

 new kind of impression necessitates a new kind of die, and, if you 

 would have a new kind of determination, you must get a new a priori 

 principle ; a given principle can not be altered to suit emergencies. 

 Experience may sharpen but not remodel it : as well expect the metal 

 to remodel the die that cuts it. An a priori principle reconstructed 

 a posteriori is an article which the author of the " Critique of Pure 

 Reason " happened never to turn out from his workshop, although, if it 

 had found entrance, he infallibly would have turned it out in double- 

 quick time. 



Yet Professor Zollner thinks not only that the "causal principle" 

 is a special agent in producing our conception of space, but that "this, 

 in particular, is to be said of the three dimensions of our present con- 

 ception of space," implying thereby, in the teeth of the Kantian dogma, 

 that we have arrived by degrees at a conception of three dimensions, 

 halting for a time at two, if not halting before at one. Indeed, Pro- 

 fessor Crookes, expounding in " The Quarterly Journal of Science" 

 Professor Zollner's theory, affirms as much explicitly. " The totality 

 of all empirical experience," he states, doubtless repeating the language 

 of his theorist, "is communicated to the intellect by the senses, i.e., 



