It is not so with red and green, for these harmonise when of the same depth. This being the case, and red being a glowing colour, if a red object is placed on a green ground, or a green object on a red ground, the "figure" and ground will appear to "swim" together, and will produce a dazzling effect. Colour must assist form, and not confuse it. It will do this in the instance just named if the figure is outlined with black, white, or gold, and there will be no loss of harmony. But experience has shown that this effect can also be averted by outlining the figure with a lighter tint of its own colour. Thus, if the figure is red and the ground green, an outline of lighter red (pink) may be employed. [(See Proposition 26, page 34.)]
A blue figure on a red ground (as ultramarine on carmine), or a red figure on a blue ground, will also produce this swimming and unsatisfactory effect, but this is again obviated by an outline of black, white, or gold.
Employing the outline thus must not be regarded as a means of merely rendering what was actually unpleasant endurable, for it does much more—it affords one of the richest means of effect. A carmine ground well covered with bold green ornament having a gold outline is, if well managed, truly gorgeous; and were the figure blue on the red ground, the lavish use of gold would render the employment of yellow unnecessary as the yellow formed in the eye and cast upon the gold would satisfy all requirements.
It is a curious fact that the eye will create any colour of which there is a deficiency. This it will do, but the colour so created is of little use to the composition unless white or gold is present; if, however, there be white or gold in the composition, the colour which is absent, or is insufficiently represented, will be formed in the eye and cast upon these neutrals, and the white or the gold, as the case may be, will assume the tint of the deficient or absent colour. [(See Propositions 8] and 9, page 32.)
While this occurs (and sometimes it occurs to a marked degree, as can be shown by experiment), it must not be supposed that a composition in which any element is wanting is as perfect as one which reveals no want. It is far otherwise; only Nature here comes to our assistance, and is content to help herself rather than endure our short-comings; but in the one case we give Nature the labour of completing the harmony; while in the other, all being prepared, we receive a sense of satisfaction and repose.
In Proposition 8 we showed that when blue and black are juxtaposed, the black becomes "rusty," or assumes an orange tint; and in Proposition 9 we gave the cause of this effect. Let a blue spot be placed on a black silk necktie, and however black the silk, it will yet appear rusty. This is a fact; but we sometimes desire to employ blue on black, and wish the black to look black, and not an orange-black. How can we do this? Obviously by substituting for the black a very dark blue, as indigo. The bright blue spot induces orange (the complement of blue) in the eye. This orange, when cast upon black, causes the latter to look "rusty;" but if we place in the black an amount of blue sufficient to neutralise the orange cast upon it, the effect will be that of a jet-black.
We have now considered those qualities of colour, and those laws of contrast and harmony, which may be said to be of the grosser sort; but we have scarcely touched on those considerations which pertain to special refinement or tenderness of effect. But let me close the part of my subject of which I have treated, by repeating a statement already made—a statement, let me say, which first led me to perceive really harmony of colour—that those colours, and those particular hues of colour, which improve each other to the utmost, are those which perfectly harmonise. (Consider this statement in connection with [Propositions 8], 9, 10, and 14, pages 32 and 33.)
We come now to consider delicacies and refinements in colour effects, which, although dependent upon the skilful exercise of the laws enunciated, are yet of a character, the power to produce which only results from the consideration of the works of the masters of great art-nations; but of these effects I can say little beyond pointing out what should be studied.
This principle however I cannot pass without notice—namely, that the finest colour effects are those of a rich, mingled, bloomy character.