derived from experience of identical things. But it is otherwise if the conceptions of causation and identity are correlative--not results of experience of which one must be formed before the other, but co-ordinate expressions of one and the same synthetic principle, which renders experience possible. And this is the real state of the case. It is true, as Hume points out, that when we want to know whether a certain sensation, precisely resembling one that we have previously experienced, represents the same object, we do so by asking how otherwise it can be accounted for. If no difference appears in its antecedents or sequents, we identify it--refer it to the same thing--as that previously experienced; for its relations (which, since it is an event in time, take the form of antecedence and sequence) _are_ the thing. The conceptions of identity and of relation in the way of cause and effect are thus as strictly correlative and inseparable as those of the thing and of its relations. Without the conception of identity experience would want a centre, without that of cause and effect it would want a circumference. Without the supposition of objects which ‘existing at one time are the same with themselves as existing at other times’--a supposition which at last, when through acquaintance with the endlessness of orderly change we have learnt that there is but one object for which such identity can be claimed without qualification, becomes the conception of nature as a uniform whole--there could be no such comparison of the relations in which an object is now presented with those in which it has been before presented, as determines us to reckon it the cause or effect of another; but it is equally true that it is only by such comparison of relations that the identity of any particular object can be ascertained. [1] P. 376. [Book I, part III., sec. II.] Hume quite right in saying that we do not go _more_ beyond sense in reasoning than in perception.