No mistake is possible here. What people attribute to Rembrandt is really his. Without any doubt chiaroscuro is the native and necessary form of his impressions and ideas. Others have made use of it; but nobody has employed it so constantly and ingeniously as he. It is the supremely mysterious form, the most enveloped, the most elliptic, and the richest in hidden meanings and surprises that exists in the pictorial language of the painter. In this sense it is more than any other the form of intimate feelings or ideas. It is light, vaporous, veiled, discreet; it lends its charm to hidden things, invites curiosity, adds an attraction to moral beauties, and gives a grace to the speculations of conscience. In short, it partakes of sentiment, emotion, uncertainty, indefiniteness, and infinity; of dreams and of the ideal. And this is why it is, as it ought to be, the poetic and natural atmosphere in which Rembrandt's genius never ceased to dwell.
In very ordinary language and in its action common to all schools, chiaroscuro is the art of rendering the atmosphere visible, and painting an object enveloped with air. Its aim is to render all the picturesque accidents of shadow, of half-tints, of light, of relief, and of distance; and to give in consequence more variety, more unity of effect, more caprice and more relative truth either to forms or to colours. The contrary is a more ingenuous and more abstract acceptation, by virtue of which objects are shown as they are, viewed close at hand, the atmosphere being suppressed, and consequently without any other than linear perspective, which results from the diminishing of objects and from their relation to the horizon. When we speak of aërial perspective, we already presuppose a little chiaroscuro.
Any other than Rembrandt, in the Dutch school, might sometimes make us forget that he was obeying the fixed laws of chiaroscuro; with him this forgetfulness is impossible: he has so to speak framed, co-ordinated and promulgated its code, and if we might believe him a _doctrinaire_ at this moment of his career, when instinct swayed him much more than reflection, the _Night Watch_ would have a redoubled interest, for it would assume the character and the authority of a manifesto.