153. Now the exquisiteness with which the painter has applied all his skill in composition, all his dexterity in touch of pencil, and all his experience of the sources of expression, to complete the rendering of his comparison, cannot, in any of the finest subtleties of it, be explained; but the first steps of its science may be easily traced; and with little pains you may see how a simple and large mass of white is opposed to a rugged one of grey; how the child's face is put in front light, that no shadow may detract from the brightness which makes her, as in Arabian legends, "a princess like to the full moon"--how, in this halo, the lips and eyes are brought out in deep and rich colour, while scarcely a gleam of reflection is allowed to disturb the quietness of the eyes;--(the terrier's, you feel, would glitter enough, if you could see them, and flash back in shallow fire; but the princess's eyes are thinking, and do not flash;)--how the quaint cap surrounds, with its not wholly painless formalism, the courtly and patient face, opposed to the rugged and undressed wild one; and how the easy grace of soft limb and rounded neck is cast, in repose, against the uneasily gathered up crouching of the short legs, and petulant shrug of the eager shoulders, in the ignobler creature. 154. Now, in his doing of all this, Sir Joshua was thinking of, and seeing, whatever was best in the creatures, within and without. Whatever was most perfectly doggish--perfectly childish--in soul and body. The absolute truth of outer aspect, and of inner mind, he seizes infallibly; but there is one part of the creatures which he never, for an instant, thinks of, or cares for,--their bones. Do you suppose that, from first to last, in painting such a picture, it would ever enter Sir Joshua's mind to think what a dog's skull would look like, beside a baby's? The quite essential facts to him are those of which the skull gives no information--that the baby has a flattish pink nose, and the dog a bossy black one. You might dissect all the dead dogs in the water supply of London without finding out, what, as a painter, it is here your only business precisely to know,--what sort of shininess there is on the end of a terrier's nose; and for the position and action of the creatures, all the four doctors together, who set Bustle's leg for him the other day, when he jumped out of a two-pair-of-stairs window to bark at the volunteers, could not have told Sir Joshua how to make his crouching terrier look ready to snap, nor how to throw the child's arm over its neck in complete, yet not languid, rest. 155. Sir Joshua, then, does not think of, or care for, anatomy, in this picture; but if he had, would it have done him harm? You may easily see that the child's limbs are not drawn with the precision that Mantegna, Dürer, or Michael Angelo would have given them. Would some of their science not have bettered the picture?