rived mental excitement was not primarily concerned with factors in Nature. The colours and the sounds were secondary factors supplied by the mental reaction. But the curious fact remained that these secondary factors are perceived as related by the spatiality which is the grand substratum of Nature. Hume was, I think, the first philosopher who explicitly pointed out this curious hybrid character of our perceptions, according to the current doctrine of the perception of secondary qualities. Though, of course, this hybrid characteristic was tacitly presupposed by Locke when he conceived colour as a secondary quality of the things in Natute, I believe that any cosmological doctrine which is faithful to the facts has to admit this artificial character of sense-perception. Namely, when we perceive the red rose we are associating out enjoyment of red detived from one source with our enjoyment of a spatial region derived from
