[Footnote 2:  “If phenomena were things in themselves no one would be able, from the succession of the representations of their manifold, to tell how this is connected in the object.”]

That which the relation of cause and effect does for the succession[1] of phenomena, the relation of reciprocity does for their coexistence, and that of substance and accident for their duration.  Since absolute time is not an object of perception, the position of phenomena in time cannot be directly determined, but only through a concept of the understanding.  When I conclude that two objects (the earth and the moon) must be coexistent, because perceptions of them can follow upon one another in both ways, I do this on the presupposition that the objects themselves reciprocally determine their position in time, hence are not isolated, but stand in causal community or a relation of reciprocal influence.  It is only on the condition of reciprocity between phenomena, through which they form a whole, that I can represent them as coexistent.

[Footnote 1:  Against the objection that cause and effect are frequently, indeed in most cases, simultaneous (e.g. the heated stove and the warmth of the room), Kant remarks that the question concerns the order of time merely, and not the lapse of time.  The ball lying on a soft cushion is simultaneous, it is true, with its effect, the depression in the cushion.  “But I, nevertheless, distinguish the two by the time relation of dynamical connection.  For if I place the ball on the cushion, its previously smooth surface is followed by a depression, but if there is a depression in the cushion (I know not whence) a leaden ball does not follow from it.”]

Coexistence and succession can be represented only in a permanent substratum; they are merely the modes in which the permanent exists.  Since time (in which all change takes place, but which itself abides and does not change) in itself cannot be perceived, the substratum of simultaneity and succession must exist in phenomena themselves:  the permanent in relation to which alone all the time relations of phenomena can be determined, is substance; that which alters is its determinations, accidents, or special modes of existing.  Alteration, i.e., origin and extinction, is true of states only, which can begin and cease to be, and not of substances, which change (sich veraendern), i.e., pass from one mode of existence into another, but do not alter (wechseln), i.e., pass from non-existence into existence, or the reverse.  It is the permanent alone that changes, and its states alone that begin and cease to be.  The origin and extinction of substances, or the increase and diminution of their quantum, would remove the sole condition of the empirical unity of time; for the time relations of the coexistent and the successive can be perceived only in an identical substratum, in a permanent, which exists always.  The law “From nothing nothing comes, and nothing