carpets or early Greek vases; but in the light of the above argument, and when compared with the productions of mature draughtsmen of all ages and countries, they cannot be said to be complete drawings, any more than the early unifacial statues of the Greeks can be called true plastic, simply because in neither case has the artist yet reached the highest possible development of corporeous conception, by which truly to interpret the solid objects of nature as we know them, and as master draughtsmen see them. An attempt should be made to explain the psycho-physiological process that must take place in the mind of the real draughtsman. When we look at an object in nature we know its length and breadth by the flat image on the retina; we see also the light and shade, which at once gives us a correct idea of the object's depth or relief. But we do not, nor could we, have this idea from the flat image on the retina alone, i.e. from the mere perception of the light and shade: our knowledge of its depth is the result of experience, i.e. of our having from infancy remarked a certain dispensation of light and shade on, and peculiar to, every form we have touched or traversed, and so, by association and inference, being early enabled to have ideas of the depth of things by their various arrangements of lights and darks without having to touch or traverse them. Nevertheless the act (generally, but by no means always, an unconscious one) of visually touching a form must necessarily take place before we can apprehend the third dimension of a form. It is, then, by the combination of the ideas derived from pure vision and the ideas derived from touch that we know the length, breadth and depth of a solid form. We have shown that the art of drawing is not an imitation, but an expression of the artist's ideas of form; therefore all drawing of forms that merely reproduces the image on the retina, and leaves unconsulted the ideas of touch, is incomplete and primitive, because it does not express a conception of form which is the result of an association of the two senses; in other words, it does not contain an idea of the object's relief or solidity. And all teaching of drawing that does not impress upon the student the necessity of combining the sense of vision with that of touch is erroneous, for it is thereby limiting him to a mechanical task, viz. the tracing of the flat image on the retina, which could be equally well done by mechanical means, or by photography alone. [Illustration: FIG. 4.]