§ VIII. This, then, will be the first great head under which we shall in future find it convenient to arrange a large number of archivolt decorations. It is the distinctively Southern and Byzantine form, and typically represented by the section _a_, of Fig. LXX.; and it is susceptible of almost every species of surface ornament, respecting which only this general law may be asserted: that, while the outside or vertical surface may properly be decorated, and yet the soffit or under surface left plain, the soffit is never to be decorated, and the outer surface left plain. Much beautiful sculpture is, in the best Byzantine buildings, half lost by being put under soffits; but the eye is led to discover it, and even to demand it, by the rich chasing of the outside of the voussoirs. It would have been an hypocrisy to carve them externally only. But there is not the smallest excuse for carving the soffit, and not the outside; for, in that case, we approach the building under the idea of its being perfectly plain; we do not look for the soffit decoration, and, of course, do not see it: or, if we do, it is merely to regret that it should not be in a better place. In the Renaissance architects, it may, perhaps, for once, be considered a merit, that they put their bad decoration systematically in the places where we should least expect it, and can seldomest see it:--Approaching the Scuola di San Rocco, you probably will regret the extreme plainness and barrenness of the window traceries; but, if you will go very close to the wall beneath the windows, you may, on sunny days, discover a quantity of panel decorations which the ingenious architect has concealed under the soffits. The custom of decorating the arch soffit with panelling is a Roman application of the Greek roof ornament, which, whatever its intrinsic merit (compare Chap. XXIX. § IV.), may rationally be applied to waggon vaults, as of St. Peter's, and to arch soffits under which one walks. But the Renaissance architects had not wit enough to reflect that people usually do not walk through windows.