The practice of drawing and painting offers the student the following problem in descriptive geometry: _to represent the three dimensions of space by means of a plane surface of two dimensions_. The Egyptians and Assyrians solved this problem by throwing down vertical objects upon one plane, which demands a great effort of abstraction on the part of the observer. European perspective, built up in the fifteenth century upon the remains of the geometric knowledge of the Greeks, is based on the monocular theory used by the latter. In this system, it is assumed that the picture is viewed with the eye fixed on a single point. Therefore the conditions of foreshortening--or distorting the actual dimensions according to the angle from which they are seen--are governed by placing in harmony the distance of the eye from the scheme of the picture, the height of the eye in relation to the objects to be depicted, and the relative position of these objects with reference to the surface employed. [Illustration: PLATE II. PORTION OF A SCROLL BY KU K'AI-CHIH British Museum, London.] But, in assuming that the picture is viewed with the eye fixed on a single point, we put ourselves in conditions which are not those of nature. The European painter must therefore compromise with the exigencies of binocular vision, modify the too abrupt fading of forms and, in fine, evade over-exact principles. Thus he arrives at a _perspective de sentiment_, which is the one used by our masters. Chinese perspective was formulated long before that of the Europeans and its origins are therefore different. It was evolved in an age when the method of superimposing different registers to indicate different planes was still being practiced in bas-reliefs. The succession of planes, one above the other, when codified, led to a system that was totally different from our monocular perspective. It resulted in a perspective as seen from a height. No account is taken of the habitual height of the eye in relation to the picture. The line of the horizon is placed very high, parallel lines, instead of joining at the horizon, remain parallel, and the different planes range one above the other in such a way that the glance embraces a vast space. Under these conditions, the picture becomes either high and narrow--a hanging picture--to show the successive planes, or broad in the form of a scroll, unrolling to reveal an endless panorama. These are the two forms best known under their Japanese names of _kakemono_ and _makimono_.[2] But the Chinese painter must attenuate the forms where they are parallel, give a natural appearance to their position on different levels and consider the degree of their reduction demanded by the various planes. Even he must compromise with binocular vision and arrive at a _perspective de sentiment_ which, like our own, while scientifically false, is artistically true. To this linear perspective is added moreover an atmospheric perspective.