To envelop and immerse everything in a bath of shadow; to plunge light itself into it only to withdraw it afterwards to make it appear more distant and radiant; to make dark waves revolve around illuminated centres, grading them, sounding them, thickening them; to make the obscurity nevertheless transparent, the half gloom easy to pierce, and finally to give a kind of permeability to the strongest colours that prevents their becoming blackness,--this is the prime condition, and these also are the difficulties of this very special art. It goes without saying, that if anyone ever excelled in this, it was Rembrandt. He did not invent, he perfected everything; and the method that he used oftener and better than anyone else bears his name.
When explained according to this tendency of the painter to express a subject only by the brilliance and obscurity of objects, the _Night Watch_ has, so to speak, no more secrets for us. Everything that might have made us hesitate is made clear. Its qualities have their _raison d'être_; and we even come to comprehend its errors. The embarrassment of the practitioner as he executes, of the designer as he constructs, of the painter as he colours, of the costumer as he attires, the inconsistency of the tone, the amphibology of the effect, the uncertainty of the time of day, the strangeness of the figures, their flashing apparition in deep shadow,--all this results here by chance from an effect conceived contrary to probability, and pursued in spite of all logic, not at all necessary, and with the following purpose: to illuminate a real scene with unreal light, that is to say, to clothe a fact with the ideal character of a vision. Do not seek for anything beyond this audacious project that mocked the painter's aims, clashed with received ideas, set up a system in opposition to customs, and boldness of spirit in opposition to manual dexterity; and the temerity of which certainly did not cease to spur him on until the day when I believe insurmountable difficulties revealed themselves, for, if Rembrandt resolved some of them, there are many that he could not resolve.
Though the patronage of art had shifted partly from the Church to the great magnates, especially the great commercial princes like the Medici at Florence, her influence was still paramount, and though secular subjects were not uncommon, the vast majority of paintings executed for patrons, whether clerical or lay, were still religious in subject. It is not therefore, surprising that among the artists of the Fifteenth Century, many of whom were monks and all Church painters, we find a distinct cleavage dividing artists whose aim was to break away from all traditions--realists--classicists--in a word, reformers, from artists who clung tenaciously to the old ideals, and whose main aim was still the perfection of devotional expression.