colour or tangibility? Is it possible without reference to something other than a possible impression? Is the idea of extension itself extended? Yet to the two latter questions, according to Hume’s express statements, the answer must be affirmative; nor can he avoid the affirmative answer to the first, to which he would properly be brought, except by equivocation. [1] [Greek ἄπειρον (apeiron) = unlimited, indefinite or infinite. Tr.] [2] It is not really in this sense that the impression of space according to Hume is a ‘compound’ one, as will appear below. It means, in effect, that colour and space are the same, and that feeling may be extended. 234. The _pièces justificatives_ for this assertion are not far to seek. Some of them have been adduced already. The idea of space, like every other idea, must be a ‘copy of an impression.’ [1] To speak of a feeling in its fainter stage as an ‘image’ of what it was in its livelier stage may, indeed, seem a curious use of terms; but in this sense only, according to Hume’s strict doctrine, can the idea of space be spoken of as an ‘image’ of anything at all. The impression from which it is derived, _i.e._ the feeling at its liveliest, cannot properly be so spoken of, for ‘no impression is presented by the senses as the image of anything distinct, or external, or independent.’ [2] If no impression is so presented, neither can any idea, which copies the impression, be so. It can involve no reference to anything which does not come and go with the impression. Accordingly no distinction is possible between space on the one hand, and either the impression or idea of it on the other. All impressions and ideas that can be said to be of extension must be themselves extended; and conversely, as Hume puts it, ‘all the qualities of extension are qualities of a perception.’ It should follow that space is either a colour or feeling of touch. In the terms which Hume himself uses with reference to ‘substance,’ ‘if it be perceived by the eyes, it must be colour; if by the ears, a sound; and so on, of the other senses.’ As he expressly tells us that it is ‘perceived by the eyes,’ the conclusion is inevitable. [1] P. 340 [Book I, part II., sec. III.] [2] P. 479 [Book I, part IV., sec. II.] The parts of space are parts of a perception.