When we see colour, we observe at least a uniform surface environed by other surfaces, from which it is differentiated by its special characteristics. If we exclude these other surfaces, we stare into nothingness and all colour is gone, or, at best, there remains only a vague feeling. [Is that so?] Closed-eye vision, again, presents a changing multitude of dots, very like pricks on the skin; but even these dots are the result of a selective or complicated process. When this process does not take place, we have no volume and no dimensions left, but merely cutaneous feelings [Is this so?] A shapeless cloud, a gust of wind, a swarm of bees, an indifferent form like that of a rock, may be regarded as having volume; but a strange medley of dots, as in dim closed-eye vision, in no way resembles masses, volumes or lines. The undeveloped man, then, is blind, and lacks a colour sense and space sense, the former sense, like the latter, arising from development. By organised attempts the chaos is reduced to cosmos, and this is done by systematically developing visual systems, singling out in this way portions of the chaos and creating points, lines, surfaces and volumes. Space, strictly speaking, has no dimensions. We have only a complex of lines, or changes in the field of visual development or attention. By persistent changes that field becomes gradually exhausted, and with it the content of space. Hence space, as we know it, is all the space possible.