§ 8. That slime we shall find in most cases composed of clay (or brickdust, which is burnt clay) mixed with soot, a little sand, and water. All these elements are at helpless war with each other, and destroy reciprocally each other's nature and power, competing and fighting for place at every tread of your foot;--sand squeezing out clay, and clay squeezing out water, and soot meddling everywhere and defiling the whole. Let us suppose that this ounce of mud is left in perfect rest, and that its elements gather together, like to like, so that their atoms may get into the closest relations possible. § 9. Let the clay begin. Ridding itself of all foreign substance, it gradually becomes a white earth, already very beautiful; and fit, with help of congealing fire, to be made into finest porcelain, and painted on, and be kept in kings' palaces. But such artificial consistence is not its best. Leave it still quiet to follow its own instinct of unity, and it becomes not only white, but clear; not only clear, but hard; not only clear and hard, but so set that it can deal with light in a wonderful way, and gather out of it the loveliest blue rays only, refusing the rest. We call it then a sapphire. Such being the consummation of the clay, we give similar permission of quiet to the sand. It also becomes, first, a white earth, then proceeds to grow clear and hard, and at last arranges itself in mysterious, infinitely fine, parallel lines, which have the power of reflecting not merely the blue rays, but the blue, green, purple, and red rays in the greatest beauty in which they can be seen through any hard material whatsoever. We call it then an opal. In next order the soot sets to work; it cannot make itself white at first, but instead of being discouraged, tries harder and harder, and comes out clear at last, and the hardest thing in the world; and for the blackness that it had, obtains in exchange the power of reflecting all the rays of the sun at once in the vividest blaze that any solid thing can shoot. We call it then a diamond. Last of all the water purifies or unites itself, contented enough if it only reach the form of a dew-drop; but if we insist on its proceeding to a more perfect consistence, it crystallizes into the shape of a star. And for the ounce of slime which we had by political economy of competition, we have by political economy of co-operation, a sapphire, an opal, and a diamond, set in the midst of a star of snow. § 10. Now invention in art signifies an arrangement, in which everything in the work is thus consistent with all things else, and helpful to all else. It is the greatest and rarest of all the qualities of art. The power by which it is effected is absolutely inexplicable and incommunicable; but exercised with entire facility by those who possess it, in many cases even unconsciously.[3]