the east than that chosen in Plate +31+. These
leading lines are rarely well shown in fine weather, the important
contour from _a_ downwards being hardly relieved clearly from the
precipice beyond (_b_), unless a cloud intervenes, as it did when I made
this memorandum; while, again, the leading lines of the Aiguille du
Plan, as seen from the foot of it, close to the rocks, are as at Fig.
38, the generally pyramidal outline being nearly similar to that of
Blaitiere, and a spur being thrown out to the right, under _a_, composed
in exactly the same manner of curved folia of rock laid one against the
other. The hollow in the heart of the aiguille is as smooth and sweeping
in curve as the cavity of a vast bivalve shell.

[Illustration: FIG. 38.]

Sec. 18. I call these the governing or leading lines, not because they are
the first which strike the eye, but because, like those of the grain of
the wood in a tree-trunk, they rule the swell and fall and change of all
the mass. In Nature, or in a photograph, a careless observer will by no
means be struck by them, any more than he would by the curves of the
tree; and an ordinary artist would draw rather the cragginess and
granulation of the surfaces, just as he would rather draw the bark and
moss of the trunk. Nor can any one be more steadfastly adverse than I to
every substitution of anatomical knowledge for outward and apparent
fact; but so it is, that as an artist increases in acuteness of
perception, the facts which _become_ outward and apparent to him are
those which bear upon the growth or make of the thing. And, just as in
looking at any woodcut of trees after Titian or Albert Durer, as
compared with a modern water-color sketch, we shall always be struck by
the writhing and rounding of the tree trunks in the one, and the
stiffness, and merely blotted or granulated surfaces of the other; so,
in looking at these rocks, the keenness of the artist's eye may almost
precisely be tested by the degree in which he perceives the curves that
give them their strength and grace, and in harmony with which the flakes
of granite are bound together, like the bones of the jaw of a saurian.
Thus the ten years of study which I have given to these mountains since
I described them in the first volume as "traversed sometimes by graceful
curvilinear fissures, sometimes by straight fissures," have enabled me
to ascertain, and now generally at a glance to see, that the curvilinear
ones are _dominant