233. ‘The first notion of space and extension,’ he says, ‘is derived solely from the senses of sight and feeling: nor is there anything but what is coloured or tangible that has parts disposed after such a manner as to convey the idea.’ Now, there may be a meaning of ‘derivation,’ according to which no one would care to dispute the first clause of this sentence. Those who hold that _really_, i.e. _for a consciousness to which the distinction between real and unreal is possible_, there is no feeling except such as is determined by thought, are yet far from holding that the determination is arbitrary; that any and every feeling is potentially any and every conception. Of the feelings to which the visual and tactual nerves are organic, as they would be for a merely feeling consciousness, nothing, they hold, can be said; in that sense they are an ἄπειρον; [1] but for the thinking consciousness, or (which is the same) as they _really_ are, these feelings do, while those to which other nerves are organic do not, form the specific possibility of the conception of space. According to this meaning of the words, all must admit that ‘the first notion of space and extension is derived from the senses of sight and feeling;’ though it does not follow that a repeated or continued activity of either sense is necessary to the continued presence of the notion. With Hume, however, the derivation spoken of must mean that the notion of space is, to begin with, simply a visual or tactual feeling, and that such it remains, though with indefinite abatement and revival in the liveliness of the feeling, according to the amount of which it is called ‘impression’ or ‘idea.’ If we supposed him to mean, not that the notion of space was either a visual or tactual feeling indifferently, but that it was a compound result of both, [2] we should merely have to meet a further difficulty as to the possibility of such composition of feelings when their inward synthesis in a soul, and the outward in a body, have been alike excluded. In the next clause of the sentence, however, we find that for visual and tactual feelings there are quietly substituted ‘coloured and tangible objects, having parts so disposed as to convey the idea of extension.’ It is in the light of this latter clause that the uncritical reader interprets the former. He reads back the plausibility of the one into the other, and, having done so, finds the whole plausible. Now this plausibility of the latter clause arises from its implying a three-fold distinction--a distinction of colour or tangibility on the one side from the disposition of the parts on the other; a distinction of the colour, tangibility and disposition of parts alike from an object to which they belong; and a distinction of this object from the idea that it conveys. In other words, it supposes a negative answer to the three following questions:--Is the idea of extension the same as that of