and, when it does follow, regard it as an effect. If I thought that the sensation of sight, however like those previously referred to flame, did not represent the same object, I should not infer heat as effect; and conversely, if, having identified the sensation of sight as representative of flame, I found that the inferred heat was not actually felt, I should judge that I was mistaken in the identification. It follows that it is only an experience of identical, and by consequence related and qualified, objects, of which the memory can so determine a sequence of feelings as to constitute it an experience of cause and effect. Thus the perception and remembrance upon which, according to Hume, we judge one object to be the cause of another, alike rest on the ‘fictions of identity and continued existence.’ Without these no present experience would, in his language, be an instance of an individual of a certain species existing in a certain relation, nor would there be a past experience of individuals of the same species, by comparison with which the constancy of the relation might be ascertained. [1] P. 388. [Book I, part III., sec. VI.] Hume makes conceptions of identity and cause each come before the other. Their true correlativity. 313. Against this derivation of the conception of cause and effect, as implying that of identity, may be urged the fact that when we would ascertain the truth of any identification we do so by reference to causes and effects. As Hume himself puts it at the outset of his discussion of causation, an inference of identity ‘beyond the impressions of our senses can be founded only on the connexion of cause and effect.’ ... ‘Whenever we discover a perfect resemblance between a new object and one which was formerly present to the senses, we consider whether it be common in that species of objects; whether possibly or probably any cause could operate in producing the change and resemblance; and according as we determine concerning these causes and effects, we form our judgment concerning the identity of the object’. [1] This admission, it may be said, though it tells against Hume’s own subsequent explanation of identity as a fiction of the imagination, is equally inconsistent with any doctrine that would treat identity as the presupposition of inference to cause or effect. Now undoubtedly if the identity of interrupted perceptions is one fiction of the imagination and the relation of cause and effect another, each resulting from ‘custom,’ to say with Hume, that we must have the idea of cause in order to arrive at the supposition of identity, is logically to exclude any derivation of that idea from an experience which involves the supposition of identity. The ‘custom’ which generates the idea of cause must have done its work before that which generates the supposition of identity can begin. Hume therefore, after the admission just quoted, was not entitled to treat the inference to cause or effect as a habit