3. Similarly, the word 'Sculpture,'--though in ultimate accuracy it is to be limited to the development of form in hard substances by cutting away portions of their mass--in broad definition, must be held to signify _the reduction of any shapeless mass of solid matter into an intended shape_, whatever the consistence of the substance, or nature of the instrument employed; whether we carve a granite mountain, or a piece of box-wood, and whether we use, for our forming instrument, ax, or hammer, or chisel, or our own hands, or water to soften, or fire to fuse;--whenever and however we bring a shapeless thing into shape, we do so under the laws of the one great art of Sculpture. 4. Having thus broadly defined painting and sculpture, we shall see that there is, in the third place, a class of work separated from both, in a specific manner, and including a great group of arts which neither, of necessity, _tint_, nor for the sake of form merely, _shape_ the substances they deal with; but construct or arrange them with a view to the resistance of some external force. We construct, for instance, a table with a flat top, and some support of prop, or leg, proportioned in strength to such weights as the table is intended to carry. We construct a ship out of planks, or plates of iron, with reference to certain forces of impact to be sustained, and of inertia to be overcome; or we construct a wall or roof with distinct reference to forces of pressure and oscillation, to be sustained or guarded against; and, therefore, in every case, with especial consideration of the strength of our materials, and the nature of that strength, elastic, tenacious, brittle, and the like. Now although this group of arts nearly always involves the putting of two or more separate pieces together, we must not define it by that accident. The blade of an oar is not less formed with reference to external force than if it were made of many pieces; and the frame of a boat, whether hollowed out of a tree-trunk, or constructed of planks nailed together, is essentially the same piece of art; to be judged by its buoyancy and capacity of progression. Still, from the most wonderful piece of all architecture, the human skeleton, to this simple one,[5] the plowshare, on which it depends for its subsistence, _the putting of two or more pieces together_ is curiously necessary to the perfectness of every fine instrument; and the peculiar mechanical work of Daedalus,--inlaying,--becomes all the more delightful to us in external aspect, because, as in the jawbone of a Saurian, or the wood of a bow, it is essential to the finest capacities of tension and resistance.