Could Hume consistently admit idea of relation at all? 208. It is his method of dealing with these ideas of philosophical relation that is specially characteristic of Hume, Let us, then, consider how the notion of relation altogether is affected by his reduction of the world of consciousness to impressions and ideas. What is an impression? To this, as we have seen, the only direct answer given by him is that it is a feeling which must be more lively before it becomes less so. [1] For a further account of what is to be understood by it we must look to the passages where the governing terms of ‘school-metaphysics’ are, one after the other, shown to be unmeaning, because not taken from impressions. Thus, when the idea of substance is to be reduced to an ‘unintelligible chimaera,’ it is asked whether it ‘be derived from the impressions of sensation or reflection? If it be conveyed to us by our senses, I ask, which of them, and after what manner? If it be perceived by the eyes, it must be a colour; if by the ears, a sound; if by the palate, a taste; and so of the other senses. But I believe none will assert that substance is either a colour, or a sound, or a taste. The idea of substance must therefore be derived from an impression of reflection, if it really exist. But the impressions of reflection resolve themselves into our passions and emotions’. [2] From the polemic against abstract ideas we learn further that ‘the appearance of an object to the senses’ is the same thing as an ‘impression becoming present to the mind’. [3] That is to say, when we talk of an impression of an object, it is not to be understood that the feeling is determined by reference to anything other than itself: it is itself the object. To the same purpose, in the criticism of the notion of an external world, we are told that ‘the senses are incapable of giving rise to the notion of the continued existence of their objects, after they no longer appear to the senses; for that is a contradiction in terms’ (since the appearance _is_ the object); and that ‘they offer not their impressions as the images of something distinct, or independent, or external, because they convey to us nothing but a single perception, and never give us the least intimation of anything beyond’. [4] The distinction between impression of sensation and impression of reflection, then, cannot, any more than that between impression and idea, be regarded as either really or apparently a distinction between outer and inner. ‘All impressions are internal and perishing existences’; [5] and, ‘everything that enters the mind being in reality as the impression, ’tis impossible anything should to feeling appear different’. [6] [1] See above, paragraphs 195 and 197. [2] p. 324 [Book I, part I., sec. VI.] [3] p. 327 [Book I, part I., sec. VII.] [4] p. 479 [Book I, part IV., sec. II.] [5] p. 483 [Book I, part IV., sec. II.] [6] p. 480 [Book I, part IV., sec. II.]