From this deficiency of effect in the composition we speak of, it is evident, that mere natural light and shade, however separately or individually true, is not always legitimate Chiaroscuro in art. Nature sheds or withholds her ray indiscriminately, and every object has what share it can obtain by place and position, which it is the business of art to arrange by fixing a centre and distributing the rays according to the more or less important claims of the subject: as long as it regulates itself by strict observance of that principle, it matters not whether its principal mass radiate from the middle, wind in undulating shapes, dart in decided beams from the extremities; emanate from one source, or borrow additional effect from subordinate ones: let it mount like flame or descend in lightning; dash in stern tones terror on the eye, emergent from a dark or luminous medium; through twilight immerse itself in impenetrable gloom or gradually vanish in voluptuous repose, guided by the subject the most daring division of light and shade becomes natural and legitimate, and the most regular, spurious and illegitimate without it. To attain in the execution the highest possible and widest expanded effect of light, with equal depth and transparence in the shade, brilliancy of colour is less required than unison: a sovereign tone must pervade the whole, which, though arbitrary and dependent on choice, decides all subordinate ones, as the tone of the first instrument in a regular concert tunes all the rest; their effect entirely depends on being in unison with it, and discord is produced whenever they revolt: by thus uniting itself with the whole, the simplest tone well managed may become, not only harmonious, but rich and splendid, it is then the tone of Nature: whilst the most brilliant one, if contradicted or disappointed by the detail of the inferior, may become heavy, leathern, and discordant. Though every work of Correggio is an illustration of this principle, and none with brighter evidence than his "Notte," in which the central light of the infant irradiates the whole; perhaps the most decisive, because the most appropriate proof of it, is in its companion the less known picture of St. Sebastian, at Dresden; in which the central light of a glory, not only surprises the eye with all the splendour of a sun, though its colour is a yellow comparatively faint, and terminates in brown, but tinges the whole, perfectly transparent, with its emanation.