Immanuel Kant's Critique of Pure Reason — trans. F. Max Müller

(It has been shown by the preceding principle, that all phenomena in the succession of time are changes only, i.e. a successive being and not-being of the determinations of the substance, which is permanent, and consequently that the being of the substance itself, which follows upon its not-being, and its not-being, which follows on its being, — in other words, that an arising or perishing of the substance itself is inadmissible. The same principle might also have been expressed thus : all change {^successions of phenomena consists in modificatio7i 07ily, for arising and perishing are no modifications of the substance, because the concept of modification presupposes the same subject as existing with two opposite determinations, and therefore as permanent. After this preliminary remark, we shall proceed to the proof.)

I perceive that phenomena succeed each other, that is, that there is a state of things at one time the opposite of which existed at a previous time. I am therefore really connecting two perceptions in time. That connection is not a work of the senses only and of intuition, but is here the product of a synthetical, power of the faculty of imagination, which determines the internal sense

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with reference to relation in time. Imagination, however, can connect those two states in two ways, so that either the one or the other precedes in time : for time cannot be perceived by itself, nor can we determine in the object empirically and with reference to time, what precedes and what follows. I am, therefore, conscious only that my imagination places the one before, the other after, and not, that in the object the one state comes before the other. In other words, the objective relation of phenomena following upon each other remains undetermined by mere perception. In order that this may be known as determined, it is necessary to conceive the relation between the two states in such a way that it should be determined thereby with necessity, which of the two should be taken as coming first, and which as second, and not conversely. Such a concept, involving a necessity of synthetical unity, can be a pure concept of the understanding only, which is not supplied by experience, and this is, in this case, the concept of the relation of cause and effect, the former determining the latter in time as the consequence, the cause not being something that might be antecedent in imagination only, or might not be perceived at all. Experience itself, therefore, that is, an empirical knowledge of phenomena, is possible only by our subjecting the succession of phenomena, and with it all change, to the law of causahty, and phenomena themselves, as objects of experience, are consequently possible according to the same law only.

SUPPLEMENT XX

[See vol. ii. p. 184]

C. Third Analogy

Principle of Coexistence^ according to the Law of Reciprocity or

Community

All substances, so far as they can be perceived as coexistent in space, are always affecting each other reciprocally.

Proof

Things are coexistent when, in empirical intuition, the perception of the one can follow upon the perception of the other, and vice versa, which, as was shown in the second principle, is impossible in the temporal succession of phenomena. Thus I may first observe the moon and afterwards the earth, or, conversely also, first the earth and afterwards the moon, and because the perceptions of these objects can follow each other in both ways, I say that they are coexistent. Now coexistence is the existence of the manifold in the same time. Time itself, however, cannot be perceived, so that we might learn from the fact that things exist in the same time that their perceptions can follow each other reciprocally. The synthesis of imagination in apprehension would, therefore, give us each of these perceptions as existing in the subject, when the other is absent, and vice ve7'sa : it would never tell us that the objects are coexistent, that is, that if the one is there, the other also must be there in the same time, and this by necessity, so that the perceptions may follow each other reciprocally. Hence we require a concept of understanding of the reciprocal sequence of determinations of things existing at the same time,

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