43. All these groups are separated by distinctions clear and bold--and many of them by that broadest of all distinctions which lies between disorganization and consistency--accumulation and adaptation, experiment and design;--yet to all one or two principles are common, which again divide the whole series from that of the Transalpine Gothic--and whose importance Lord Lindsay too lightly passes over in the general description, couched in somewhat ungraceful terms, "the vertical principle snubbed, as it were, by the horizontal." We have already alluded to the great school of color which arose in the immediate neighborhood of the Genoa serpentine. The accessibility of marble throughout North Italy similarly modified the aim of all design, by the admission of undecorated surfaces. A blank space of freestone wall is always uninteresting, and sometimes offensive; there is no suggestion of preciousness in its dull color, and the stains and rents of time upon it are dark, coarse, and gloomy. But a marble surface receives in its age hues of continually increasing glow and grandeur; its stains are never foul nor dim; its undecomposing surface preserves a soft, fruit-like polish forever, slowly flushed by the maturing suns of centuries. Hence, while in the Northern Gothic the effort of the architect was always so to diffuse his ornament as to prevent the eye from permanently resting on the blank material, the Italian fearlessly left fallow large fields of uncarved surface, and concentrated the labor of the chisel on detached portions, in which the eye, being rather directed to them by their isolation than attracted by their salience, required perfect finish and pure design rather than force of shade or breadth of parts; and further, the intensity of Italian sunshine articulated by perfect gradations, and defined by sharp shadows at the edge, such inner anatomy and minuteness of outline as would have been utterly vain and valueless under the gloom of a northern sky; while again the fineness of material both admitted of, and allured to, the precision of execution which the climate was calculated to exhibit.