These being what we have usually to deal with, Nature seems to have set herself to make these three substances as interesting to us, and as beautiful for us, as she can. The clay, being a soft and changeable substance, she doesn't take much pains about, as we have seen, till it is baked; she brings the colour into it only when it receives a permanent form. But the limestone and flint she paints, in her own way, in their native state: and her object in painting them seems to be much the same as in her painting of flowers; to draw us, careless and idle human creatures, to watch her a little, and see what she is about--that being on the whole good for us,--her children. For Nature is always carrying on very strange work with this limestone and flint of hers: laying down beds of them at the bottom of the sea; building islands out of the sea; filling chinks and veins in mountains with curious treasures; petrifying mosses, and trees, and shells; in fact, carrying on all sorts of business, subterranean or submarine, which it would be highly desirable for us, who profit and live by it, to notice as it goes on. And apparently to lead us to do this, she makes picture-books for us of limestone and flint; and tempts us, like foolish children as we are, to read her books by the pretty colours in them. The pretty colours in her limestone-books form those variegated marbles which all mankind have taken delight to polish and build with from the beginning of time; and the pretty colours in her flint-books form those agates, jaspers, cornelians, bloodstones, onyxes, cairngorms, chrysoprases, which men have in like manner taken delight to cut, and polish, and make ornaments of, from the beginning of time; and yet, so much of babies are they, and so fond of looking at the pictures instead of reading the book, that I question whether, after six thousand years of cutting and polishing, there are above two or three people out of any given hundred, who know, or care to know, how a bit of agate or a bit of marble was made, or painted. How it was made, may not be always very easy to say; but with what it was painted there is no manner of question. All those beautiful violet veinings and variegations of the marbles of Sicily and Spain, the glowing orange and amber colours of those of Siena, the deep russet of the Rosso antico, and the blood-colour of all the precious jaspers that enrich the temples of Italy; and, finally, all the lovely transitions of tint in the pebbles of Scotland and the Rhine, which form, though not the most precious, by far the most interesting portion of our modern jewellers' work;--all these are painted by nature with this one material only, variously proportioned and applied--the oxide of iron that stains your Tunbridge springs.