Only since this signifies nothing other than the concept of a subsisting object in general, insofar as one thinks in it merely the transcendental subject without any predi cates, but here only the unconditioned in a series of appearances is under discussion, it is clear that the substantial cannot constitute a member of thatY The same holds for substances in community, which are mere aggregates and have no exponents of a series, since they are not subordinated to one another as conditions of their possibility, which one could very well have said about spaces, whose boundaries were never determined in themselves, but always through another space.