these materials no objective idea arises: this absolutely demands the relation of the idea to its cause, thus the application of the law of causality, and thus understanding; for without this the sensation still remains always subjective, and does not take the form of an object in space, even if space is given with it. But according to Kant, the understanding must not be assigned to perception; it is supposed merely to _think_, so as to remain within the transcendental logic. With this again is connected another mistake of Kant’s: that he left it to me to adduce the only valid proof of the _a priori_ nature of the law of causality which he rightly recognised, the proof from the possibility of objective empirical perception itself, and instead of it gives a palpably false one, as I have already shown in my essay on the principle of sufficient reason, § 23. From the above it is clear that Kant’s “object of the idea” (2) is made up of what he has stolen partly from the idea (1), and partly from the thing in itself (3). If, in reality, experience were only brought about by the understanding applying its twelve different functions in order to _think_ through as many conceptions _a priori_, the objects which were previously merely perceived, then every real thing would necessarily as such have a number of determinations, which, as given _a priori_, absolutely could not be thought away, just like space and time, but would belong quite essentially to the existence of the thing, and yet could not be deduced from the properties of space and time. But only one such determination is to be found—that of causality. Upon this rests materiality, for the essence of matter consists in action, and it is through and through causality (_cf._ Bk. II. ch. iv.) But it is materiality alone that distinguishes the real thing from the picture of the imagination, which is then only idea. For matter, as permanent, gives to the thing permanence through all time, in respect of its matter, while the forms change in conformity with causality. Everything else in the thing consists either of determinations of space or of time, or of its empirical properties, which are all referable to its activity, and are thus fuller determinations of causality. But causality enters already as a condition into the empirical perception, and this is accordingly a thing of the understanding, which makes even perception possible, and yet apart from the law of causality contributes nothing to experience and its possibility. What fills the old ontologies is, with the exception of what is given here, nothing more than relations of things to each other, or to our reflection, and a farrago of nonsense.