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THE PERCEPTION OF SPACE. (l.) 3 as opposed to depth ; * volume ' being the best short name for the sensation in question. Sensations of different orders are roughly comparable, inter se, with Respect to their volumes. This shows that the spatial quality in each is identical wherever found, for different qualitative elements, e.g., warmth and odour, are incommensurate. Persons born blind are reported surprised at the largeness with which objects appear to them when their sight is restored. Franz says of his patient cured of cataract : " He saw everything much larger than he had supposed from the idea obtained by his sense of touch. Moving, and especially living, objects appeared very large." Loud sounds have a certain enormousness of feel- ing. It is impossible to conceive of the explosion of a cannon as filling a small space. In general, sounds seem to occupy all the room between us and their source ;. and in the case of certain ones, the cricket's song, the whistling of the wind, the roaring of the surf, or a distant railway train, to have no definite starting point. In the sphere of vision we have facts of the same order. " Glowing" bodies, as Hering says, give us a perception " which seems roomy (raumhuft) in comparison with that of strictly surface colour. A glowing iron looks luminous through and through, and so does a flame." l A luminous fog, a band of sunshine, affect us in the same way. As Hering urges : " We must distinguish, roomy from superficial, as well as distinctly from indistinctly bounded, sensations. The dark which with closed eyes. one sees before one is for example a roomy sensation. We do not see a black surface like a wall in front of us, but a space filled with darkness, and even when we succeed in seeing this darkness as terminated by. a black wall there still remains in front of this wall the dark space. The same thing happens when we find ourselves with open eyes in an absolutely dark room. This sensation of darkness is also vaguely bounded. An example of a distinctly bounded roomy sensation is that of a clear and coloured fluid seen in a glass ; the yellow of the wine is seen not only on the bounding surface of the glass ; the yellow sensation fills the whole interior of the glass. By day the so-called empty space between us and objects seen appears very different from what it is by night. The increasing darkness settles not only upon the things but also between us and the things, so as at last to cover them completely and fill the space alone. If I look into a dark box I find it filled with darkness, and this is seen not merely as the dark-coloured sides or walls of the box. A shady corner in an otherwise well-lighted room is full of a darkness which is not only on the walls and floor but between them in the space they include. Every sensation is there where I experience it, and if 1 have it at once at every point of a certain roomy space, it is then a voluminous sensation. A cube of transparent green glass gives us a spatial sensation ; an opaque cube painted green, on the contrary, only sensations of surface." a 1 Hermann's Handb. d. Physiol, Bd. iii. 1, s. 575. 2 Ibid., s. 572.