- Konigsberg, April 1787.
the external sense is necessarily connected with that of the internal, in order to the possibility of experience in general; that is, I am just as certainly conscious that there are things external to me related to my sense as I am that I myself exist as determined in time. But in order to ascertain to what given intuitions objects, external me, really correspond, in other words, what intuitions belong to the external sense and not to imagination, I must have recourse, in every particular case, to those rules according to which experience in general (even internal experience) is distinguished from imagination, and which are always based on the proposition that there really is an external experience. We may add the remark that the representation of something permanent in existence, is not the same thing as the permanent representation; for a representation may be very variable and changing—as all our representations, even that of matter, are—and yet refer to something permanent, which must, therefore, be distinct from all my representations and external to me, the existence of which is necessarily included in the determination of my own existence, and with it constitutes one experience—an experience which would not even be possible internally, if it were not also at the same time, in part, external. To the question How? we are no more able to reply, than we are, in general, to think the stationary in time, the coexistence of which with the variable, produces the conception of change.
