Gold and silver, and everything that is mined, and all that the art of tree felling and any lopping cuts and provides for the art of the carpenter and the basket weaver and again the art of stripping off the outer covering of plants, and the one that removes skins from bodies of living things, the art of the skinner; and all the sorts of expertise there are in relation to such things, which by producing cork, and papyrus, and materials for bindings make possible the working up of classes of composite things from classes of things that are not put together.