The principle of the _Permanence of Substance_ is deduced from the category of subsistence and inherence. This, however, we know only from the form of the categorical judgment, _i.e._, from the connection of two concepts as subject and predicate. With what violence then is that great metaphysical principle made dependent upon this simple, purely logical form! Yet this is only done _pro forma_, and for the sake of symmetry. The proof of this principle, which is given here, sets entirely aside its supposed origin in the understanding and in the category, and is based upon the pure intuition or perception of time. But this proof also is quite incorrect. It is false that in mere time there is _simultaneity_ and _duration_; these ideas only arise from the union of _space_ with time, as I have already shown in the essay on the principle of sufficient reason, § 18, and worked out more fully in § 4 of the present work. I must assume a knowledge of both these expositions for the understanding of what follows. It is false that time _remains_ the same through all change; on the contrary, it is just time itself that is fleeting; a permanent time is a contradiction. Kant’s proof is untenable, strenuously as he has supported it with sophisms; indeed, he falls into the most palpable contradictions. Thus, after he has falsely set up co-existence as a mode of time (p. 177; V. 219), he says, quite rightly (p. 183; V. 226), “Co-existence is not a mode of time, for in time there are absolutely no parts together, but all in succession.” In truth, space is quite as much implicated in co-existence as time. For if two things are co-existent and yet not one, they are different in respect of space; if two states of one thing are co-existent (_e.g._, the glow and the heat of iron), then they are two contemporaneous effects of _one_ thing, therefore presuppose matter, and matter presupposes space. Strictly speaking, co-existence is a negative determination, which merely signifies that two things or states are not different in respect of time; thus their difference is to be sought for elsewhere. But in any case, our knowledge of the permanence of substance, _i.e._, of matter, must be based upon insight _a priori_; for it is raised above all doubt, and therefore cannot be drawn from experience. I deduce it from the fact that the principle of all becoming and passing away, the law of causality, of which we are conscious _a priori_, is essentially concerned only with the _changes_, _i.e._, the successive _states_ of matter, is thus limited to the form, and leaves the matter untouched, which therefore exists in our consciousness as the foundation of all things, which is not subject to becoming or passing away, which has therefore always been and will always continue to be. A deeper proof of the permanence of substance, drawn from the analysis of our perception of the empirical world in general, is to be found in the first book of this