Turning our attention first to movement—which, by the way, is not the same as motion, mere change of place—we find that we realise it just as we realise objects, by the stimulation of our tactile imagination, only that here touch retires to a second place before the muscular feelings of varying pressure and strain. I see (to take an example) two men wrestling, but unless my retinal impressions are immediately translated into images of strain and pressure in my muscles, of resistance to my weight, of touch all over my body, it means nothing to me in terms of vivid experience—not more, perhaps, than if I heard some one say “Two men are wrestling.” Although a wrestling match may, in fact, contain many genuinely artistic elements, our enjoyment of it can never be quite artistic; we are prevented from completely realising it not only by our dramatic interest in the game, but also, granting the possibility of being devoid of dramatic interest, by the succession of movements being too rapid for us to realise each completely, and too fatiguing, even if realisable. Now if a way could be found of conveying to us the realisation of movement without the confusion and the fatigue of the actuality, we should be getting out of the wrestlers more than they themselves can give us—the heightening of vitality which comes to us whenever we keenly realise life, such as the actuality itself would give us, plus the greater effectiveness of the heightening brought about by the clearer, intenser, and less fatiguing realisation. This is precisely what the artist who succeeds in representing movement achieves: making us realise it as we never can actually, he gives us a heightened sense of capacity, and whatever is in the actuality enjoyable, he allows us to enjoy at our leisure. In words already familiar to us, he extracts the significance of movements, just as, in rendering tactile values, the artist extracts the corporeal significance of objects. His task is, however, far more difficult, although less indispensable:—it is not enough that he should extract the values of what at any given moment is an actuality, as is an object, but what at no moment really is—namely movement. He can accomplish his task in only one way, and that is by so rendering the one particular movement that we shall be able to realise all other movements that the same figure may make. “He is grappling with his enemy now,” I say of my wrestler. “What a pleasure to be able to realise in my own muscles, on my own chest, with my own arms and legs, the life that is in him as he is making his supreme effort! What a pleasure, as I look away from the representation, to realise in the same manner, how after the contest his muscles will relax, and rest trickle like a refreshing stream through his nerves!” All this I shall be made to enjoy by the artist who, in representing any one movement, can give me the logical sequence of visible strain and pressure in the parts and muscles.

It is just here that the scientific spirit of the Florentine naturalists was of immense service to art. This logic of sequence is to be attained only by great, although not necessarily more than empiric, knowledge of anatomy, such perhaps as the artist pure would never be inclined to work out for himself, but just such as would be of absorbing interest to those scientists by temperament and artists by profession whom we have in Pollaiuolo and, to a less extent, in Verrocchio. We remember how Giotto contrived to render tactile values. Of all the possible outlines, of all the possible variations of light and shade that a figure may have, he selected those that we must isolate for special attention when we are actually realising it. If instead of figure, we say figure in movement, the same statement applies to the way Pollaiuolo rendered movement—with this difference, however, that he had to render what in actuality we never can perfectly isolate, the line and light and shade most significant of any given action. This the artist must construct himself out of his dramatic feeling for pressure and strain and his ability to articulate the figure in all its logical sequences, for, if he would convey a sense of movement, he must give the line and the light and shade which will best render not tactile values alone, but the sequences of articulations.