Hokusai.
CXLII
When you are painting put a piece of black velvet between your eye and nature; by this means you will easily convince yourself that in nature everything is blond, even the dark trunks of trees relieved against the sky. Black, when it is in shadow, is strong in tone, but ceases to be black.
Dutilleux.
CXLIII
The Variation of Colour in uneven Superficies, is what confounds an unskilful Painter; but if he takes Care to mark the Outlines of his Superficie, and the Seat of his Lights, he will find the true Colouring no such difficult matter: For first he will alter the Super
ficies properly as far as the Line of Separation, either with White or Black sparingly as only with gentle Dew; then he will in the same Manner bedew the other Side of the Line, if I may be allowed the expression, then this again and so on by turns, till the light Side is brightened with more transparent Colour, and the same Colour on the other Side dies away like Smoak into an easy Shade. But you should always remember, that no Superficie should ever be made so white that you cannot make it still brighter: Even in Painting the whitest Cloaths you should abstain from coming near the strongest of that Colour; because the Painter has nothing but White wherewith to imitate the Polish of the most shining Superficie whatsoever, as I know of none but Black with which he can represent the utmost Shade and Obscurity of Night. For this Reason, when he paints a white Habit, he should take one of the four Kinds of Colours that are clear and open; and so again in painting any black Habit, let him use another Extream, but not absolute Black, as for Instance, the Colour of the Sea where it is very deep, which is extreamly dark. In a Word, this Composition of Black and White has so much Power, that when practised with Art and Method, it is capable of representing in Painting the Superficie either of Gold or of Silver, and even of the clearest Glass. Those Painters, therefore, are greatly to be condemned, who make use of White immoderately and of Black without Judgment; for which reason I could wish that the Painters were obliged to buy their White at a greater
Price than the most costly Gems, and that both White and Black were to be made of those Pearls which Cleopatra dissolved in Vinegar; that they might be more chary of it.