And the first broad conclusion we shall deduce from observance of natural color in such cases will be, that it never follows form, but is arranged on an entirely separate system. What mysterious connection there may be between the shape of the spots on an animal's skin and its anatomical system, I do not know, nor even if such a connection has in any wise been traced: but to the eye the systems are entirely separate, and in many cases that of color is accidentally variable. The stripes of a zebra do not follow the lines of its body or limbs, still less the spots of a leopard. In the plumage of birds, each feather bears a part of the pattern which is arbitrarily carried over the body, having indeed certain graceful harmonies with the form, diminishing or enlarging in directions which sometimes follow, but also not unfrequently oppose, the directions of its muscular lines. Whatever harmonies there may be, are distinctly like those of two separate musical parts, coinciding here and there only--never discordant, but essentially different I hold this, then, for the first great principle of architectural color. Let it be visibly independent of form. Never paint a column with vertical lines, but always cross it.[13] Never give separate mouldings separate colors (I know this is heresy, but I never shrink from any conclusions, however contrary to human authority, to which I am led by observance of natural principles); and in sculptured ornaments I do not paint the leaves or figures (I cannot help the Elgin frieze) of one color and their ground of another, but vary both the ground and the figures with the same harmony. Notice how Nature does it in a variegated flower; not one leaf red and another white, but a point of red and a zone of white, or whatever it may be, to each. In certain places you may run your two systems closer, and here and there let them be parallel for a note or two, but see that the colors and the forms coincide only as two orders of mouldings do; the same for an instant, but each holding its own course. So single members may sometimes have single colors: as a bird's head is sometimes of one color and its shoulders another, you may make your capital of one color and your shaft another; but in general the best place for color is on broad surfaces, not on the points of interest in form. An animal is mottled on its breast and back, rarely on its paws or about its eyes; so put your variegation boldly on the flat wall and broad shaft, but be shy of it in the capital and moulding; in all cases it is a safe rule to simplify color when form is rich, and vice versâ; and I think it would be well in general to carve all capitals and graceful ornaments in white marble, and so leave them. XXXVII. Independence then being first secured, what kind of limiting outlines shall we adopt for the system of color itself?