I can show you exactly the sort of influence their science would have had. In your Rudimentary Series, I have placed in sequence two of Dürer's most celebrated plates (R. 65, R. 66), the coat of arms with the skull, and the Madonna crowned by angels; and that you may see precisely what qualities are, and are not, in this last, I have enlarged the head by photography, and placed it in your Reference Series (117). You will find the skull is perfectly understood, and exquisitely engraved, but the face, imperfectly understood and coarsely engraved. No man who has studied the skull as carefully as Dürer did, ever could engrave a face beautifully, for the perception of the bones continually thrusts itself upon him in wrong places, and in trying to conquer or modify it, he distorts the flesh. Where the features are marked, and full of character, he can quit himself of the impression; but in the rounded contour of women's faces he is always forced to think of the skull; and even in his ordinary work often draws more of bones and hair, than face. 156. I could easily give you more definite, but very disagreeable, proofs of the evil of knowing the anatomy of the human face too intimately: but will rather give you further evidence by examining the skull and face of the creature who has taught us so much already,--the eagle. Here is a slight sketch of the skull of the golden eagle. It may be interesting to you sometimes to make such drawings roughly for the sake of the points of mechanical arrangement--as here in the circular bones of the eye-socket; but don't suppose that drawing these a million of times over will ever help you in the least to draw an eagle itself. On the contrary, it would almost to a certainty hinder you from noticing the essential point in an eagle's head--the projection of the brow. All the main work of the eagle's eye is, as we saw, in looking down. To keep the sunshine above from teasing it, the eye is put under a triangular penthouse, which is precisely the most characteristic thing in the bird's whole aspect. Its hooked beak does not materially distinguish it from a cockatoo, but its hooded eye does. But that projection is not accounted for in the skull; and so little does the anatomist care about it, that you may hunt through the best modern works on ornithology, and you will find eagles drawn with all manner of dissections of skulls, claws, clavicles, sternums, and gizzards; but you won't find so much as one poor falcon drawn with a falcon's eye.