109. Have you ever looked attentively at the study I gave you of the head of the rattle-snake? The serpent will keep its eyes fixed on you for an hour together, a vertical slit in each admitting such image of you as is possible to the rattlesnake retina, and to the rattlesnake mind. How much of you do you think it sees? I ask that, first, as a pure physical question. I do not know; it is not my business to know. You, from your schools of physical science, should bring me answer. How much of a man can a snake see? What sort of image of him is received through that deadly vertical cleft in the iris;—through the glazed blue of the ghastly lens? Make me a picture of the appearance of a man, as far as you can judge it can take place on the snake’s retina. Then ask yourselves, farther, how much of speculation is possible to the snake, touching this human aspect?
110. Or, if that seem too far beneath possible inquiry, how say you of a tiger’s eye, or a cat’s? A cat may look at a king;—yes; but can it see a king when it looks at him? The beasts of prey never seem to me to look, in our sense, at all. Their eyes are fascinated by the motion of anything, as a kitten’s by a ball;—they fasten, as if drawn by an inevitable attraction, on their food. But when a cat caresses you, it never looks at you. Its heart seems to be in its back and paws, not its eyes. It will rub itself against you, or pat you with velvet tufts, instead of talons; but you may talk to it an hour together, yet not rightly catch its eye. Ascend higher in the races of being—to the fawn, the dog, the horse; you will find that, according to the clearness of sight, is indeed the kindness of sight, and that at last the noble eyes of humanity look through humanity, from heart into heart, and with no mechanical vision. And the Light of the body is the eye—yes, and in happy life, the light of the heart also.
111. But now note farther: there is a mathematical power in the eye which may far transcend its moral power. When the moral power is feeble, the faculty of measurement, or of distinct delineation, may be supreme; and of comprehension none. But here, again, I want the help of the physical science schools. I believe the eagle has no scent, and hunts by sight, yet flies higher than any other bird. Now, I want to know what the appearance is to an eagle, two thousand feet up, of a sparrow in a hedge, or of a partridge in a stubble-field. What kind of definition on the retina do these brown spots take to manifest themselves as signs of a thing eatable; and if an eagle sees a partridge so, does it see everything else so? And then tell me, farther, does it see only a square yard at a time, and yet, as it flies, take summary of the square yards beneath it? When next you are travelling by express sixty miles an hour, past a grass bank, try to see a grasshopper, and you will get some idea of an eagle’s optical business, if it takes only the line of ground underneath it. Does it take more?
112. Then, besides this faculty of clear vision, you have to consider the faculty of metric vision. Neither an eagle, nor a kingfisher, nor any other darting bird, can see things with both their eyes at the same time as completely as you and I can; but think of their faculty of measurement as compared with ours! You will find that it takes you months of labour before you can acquire accurate power, even of deliberate estimate of distances with the eye; it is one of the points to which, most of all, I have to direct your work. And the curious thing is that, given the degree of practice, you will measure ill or well with the eye in proportion to the quantity of life in you. No one can measure with a glance, when they are tired. Only the other day I got half an inch out of a foot, in drawing merely a coat of arms, because I was tired. But fancy what would happen to a swallow, if it was half an inch out in a foot, in flying round a corner!
113. Well, that is the first branch of the questions which we want answered by optical science;—the actual distortion, contraction, and other modification, of the sight of different animals, as far as it can be known from the forms of their eyes. Then, secondly, we ourselves need to be taught the connection of the sense of colour with health; the difference in the physical conditions which lead us to seek for gloom, or brightness of hue; and the nature of purity in colour, first in the object seen, and then in the eye which prefers it.
(The portion of lecture here omitted referred to illustrations of vulgarity and delicacy in colour, showing that the vulgar colours, even when they seemed most glaring, were in reality impure and dull; and destroyed each other by contention; while noble colour, intensely bright and pure, was nevertheless entirely governed and calm, so that every colour bettered and aided all the rest.)
114. You recollect how I urged you in my opening course of lectures rather to work in the school of crystalline colour than in that of shade.
Since I gave that first course of lectures, my sense of the necessity of this study of brightness primarily, and of purity and gaiety beyond all other qualities, has deeply been confirmed by the influence which the unclean horror and impious melancholy of the modern French school—most literally the school of death—has gained over the popular mind. I will not dwell upon the evil phrenzy to-day. But it is in order, at once to do the best I can, in counteraction of its deadly influence, though not without other and constant reasons, that I give you heraldry, with all its splendour and its pride, its brightness of colour, and honourableness of meaning, for your main elementary practice.