A very fine surface decoration was invented, or carried to perfection, by André Charles Boule, for Louis XIV. It is a veneer of tortoise-shell and brass, with occasional white metal. An important element in Boule decoration is noticeable in the chiselled angle mounts, lines of moulding, claws, feet, etc., all of which are imposed, though they have the general character of metal angle supports. In fact, the tortoise-shell is held by glue, and the metal by fine nails of the same material, the heads of which are filed down. Incrustation, or _marquetry_, of this kind is costly, and most of it is due to the labours of artists and craftsmen employed by the kings of France at the expense of the Government. A considerable quantity of it is still made in that country.
Now as to the way in which sculptors, or incrusters, should dispose of their decoration, and the fidelity to nature which is to be expected of them, whether in sculpture or wood mosaic, _i.e._ wood painting. First, we may suppose they will concentrate their more important details in recognisable divisions of their pieces, or in such ways that a proportion and rhythm shall be expressed by their dispositions of masses and fine details; placing their figures in central panels, on angles, or on dividing members; leaving some plain surface to set off their decorative detail; and taking care that the contours of running mouldings shall not be lost sight of by the carver. But how far is absolute natural truth, even absolute obedience to the laws of his art in every particular of his details, to be expected from the artist? We cannot doubt that such absolute obedience is sometimes departed from intentionally and with success. All Greek sculpture is not always absolutely true to nature nor as beautiful as the sculptor, if free, could have made it. Statues are conventionalised, decorative scrolls exaggerated, figures turned into columns for good reasons, and in the result successfully. In furniture, as in architecture, carved work or incrustation is not _free_, but is in _service_; and compromises with verisimilitude to nature, even violence, may sometimes be required on details in the interests of the entire structure.