310. ‘Ideas that we _have not_;’ for no one of the fictions by which we elude the contradictions, nor indeed any one of the contradictory judgments themselves, can be taken to represent an ‘idea’ according to Hume’s account of ideas. He allows himself indeed to speak of our having ideas of identical objects, such as _this table while I see or touch it_--though in this case, as has been shown, either the object is not identical or the idea of it cannot be copied from an impression--and of our transferring this idea to resembling but interrupted perceptions. But the supposition to which the contradiction involved in this transference gives rise--the supposition that the perception continues to exist when it is not perceived--is shown by the very statement of it to be no possible copy of an impression. Yet according to Hume it is a ‘belief,’ and a belief is ‘a lively idea associated with a present impression.’ What then is the impression and what the associated idea? ‘As the propensity to feign the continued existence of sensible objects arises from some lively impressions of the memory, it bestows a vivacity on that fiction; or, in other words, makes us believe the continued existence of body’. [1] Well and good: but this only answers the first part of our question. It tells us what are the impressions in the supposed case of belief, but not what is the associated idea to which their liveliness is communicated. To say that it arises from a propensity to feign, strong in proportion to the liveliness of the supposed impressions of memory, does not tell us of what impression it is a copy. Such a propensity indeed would be an ‘impression of reflection,’ but the fiction itself is neither the propensity nor a copy of it. The only possible supposition left for Hume would be that it is a ‘compound idea;’ but what combination of ‘perceptions’ can amount to the existence of perceptions when they are not perceived? [1] P. 496. [Book I, part IV., sec. II.] Comparison of present experience with past, which yields relation of cause and effect, pre-supposes judgment of identity;