superiority in the artists of his time.  “How much,” he says, “do painters see in shadow and relief that we do not see!” Yet their perception seems strangely limited to us.  The ancients had little notion of perspective.  Their eyes were too sure and too well-practised to overlook the effect of position in foreshortening objects, and they were much experienced in the corrections required, and the effect of converging lines in increasing apparent distance was taken advantage of in their theatre-scenes.  But they had not learned that the difference between the actual and the apparent form is thorough-going, so that the picture no longer stands in the attitude of passive indifference towards the beholder, but imposes upon him its own point of view.  It was thought remarkable in the Minerva of Fabullus, that it had the appearance of always looking at the spectator, from whatever point it was viewed.  This would be miraculous in a statue, and must seem so in the picture so long as it is looked upon only as one side of a statue.  The wall-paintings of Pompeii, doubtless copies or reminiscences of Greek originals,—­with masterly skill in the parts, and with some success in the landscape as far as it was easily reducible to one plane,—­are only collections of fragments, and show utter incapacity to see the whole at once as a picture.  For instance, in one of the many pictures of Narcissus beholding himself in the well, the head, which is inclined sideways, instead of being simply inverted in the reflection, is reversed,—­so that the chin, which is on the spectator’s left in the figure, is on the right in the reflected image:  as if the artist, knowing no other way, had placed himself head downwards, and in that position had repeated the face as already painted.  Such a blunder could not originate with a copyist, for it would have been much easier to copy correctly.  It is clear from the general excellence of the figure that it is not the work of an inferior artist.  Nor can it have come from mere carelessness; it is too elaborate for that,—­and, moreover, here is the main point of the picture, that which tells the story.  Doubtless the painter had noticed the pleasingness of such reflections, as repeating the human form, the supreme object of interest; but the interest stopped there.  He saw the face above and the face below, as he would see the different sides of a statue; but so incapable was he of perceiving the connection and interdependence of them, that, even when Nature had made the picture for him, he could not see it.  This is no isolated, casual mistake, but only a good chance to see what is really universal, though not often so obvious.