The next paragraph, of which the interpretation is difficult, appears to introduce a causal rule, i. e. an irreversibility in objects, by identifying it with the irreversibility in our perceptions of which Kant has been speaking. The first step to this identification is taken by the assertion: "In the present case, therefore, I shall have to derive the subjective sequence of perceptions from the objective sequence of phenomena.... The latter will consist in the order of the _manifold of the phenomenon_, according to which _the apprehension_ of the one (that which happens) follows that of the other (that which precedes) according to a rule."[36] Here Kant definitely implies that an objective sequence, i. e. an order or sequence of the _manifold_ of a phenomenon, consists in a sequence of _perceptions or apprehensions_ of which the order is necessary or according to a rule; in other words, that a succession of perceptions in the special case where the succession is necessary is a succession of events perceived.[37] This implication enables us to understand the meaning of the assertion that 'we must therefore derive the subjective sequence of perceptions from the objective sequence of phenomena', and to see its connexion with the preceding paragraph. It means, 'in view of the fact that in all apprehensions of a succession, and in them alone, the sequence of perceptions is irreversible, we are justified in saying that a given sequence of perceptions is the apprehension of a succession, if we know that the sequence is irreversible; in that case we must be apprehending a real succession, for an irreversible sequence of perceptions _is_ a sequence of events perceived.' Having thus implied that irreversibility of perceptions constitutes them events perceived, he is naturally enough able to go on to speak of the irreversibility of perceptions as if it were the same thing as an irreversibility of events perceived, and thus to bring in a causal rule. "In this way alone [i. e. only by deriving the subjective from the objective sequence] can I be justified in saying of the phenomenon itself, and not merely of my apprehension, that a sequence is to be found therein, _which is the same as to say_ that I cannot _arrange_ my apprehension otherwise than in just this sequence. In conformity with _such a rule_, therefore, there must exist in that which in general precedes _an event_ the condition of a rule, according to which _this event follows always and necessarily_."[38] Here the use of the word 'arrange'[39] and the statement about the rule in the next sentence imply that Kant has now come to think of the rule of succession as a causal rule relating to the objective succession. Moreover, if any doubt remains as to whether Kant really confuses the two irreversibilities or necessities of succession, it is removed by the last paragraph of the passage quoted. "If therefore we experience that something happens, we always thereby presuppose that something