281. We now know the nature of that preliminary manipulation which ‘impressions and ideas’ have to undergo, if their association is to yield the result which Hume requires--if through it the succession of feelings is to become a knowledge of things and their relations. Such a result was required as the only means of maintaining together the two characteristic positions of Locke’s philosophy; that, namely, the only world we can know is the world of ‘ideas,’ and that thought cannot originate ideas. Those relations, which Locke had inconsistently treated at once as intellectual superinductions and as ultimate conditions of reality, must be dealt with by one of two methods. They must be reduced to impressions where that could plausibly be done: where it could not, it must be admitted that we have no ideas of them, but only ‘tendencies to suppose’ that we have such, arising from the association, through ‘natural relations,’ of the ideas that we have. So dexterously does Hume work the former method that, of all the ‘philosophical relations’ which he recognizes, only Identity and Causation remain to be disposed of by the latter; and if the other relations--resemblance, time and space, proportion in quantity and degree in quality--could really be admitted as data of sense, there would at least be a possible basis for those ‘tendencies to suppose’ which, in the absence of any corresponding ideas, the terms ‘Identity’ and ‘Causation’ must be taken to represent. But, as we have shown, they can only be claimed for sense, if sense is so far one with thought--one not by conversion of thought into sense but by taking of sense into thought--as that Hume’s favourite appeals to sense against the reality of intelligible relations become unmeaning. They may be ‘impressions,’ there may be ‘impressions of them,’ but only if we deny of the impression what Hume asserts of it, and assert of it what he denies--only if we understand by ‘impression’ not an ‘internal and perishing existence;’ not that which, if other than taste, colour, sound, smell or touch, must be a ‘passion or emotion ‘; _not_ that which carries no reference to an object other than itself, and which must _either_ be single _or_ compound; but something permanent and constituted by permanently coexisting parts; something that may ‘be conjoined with’ any feeling, because it is none; that always carries with it a reference to a subject which it is not but of which it is a quality; and that is both many and one, since ‘in its simplicity it contains many different resemblances and relations.’