First of all it should be remembered that the intensity of color should be carefully adjusted to its area.  It is dangerous to try to use high, pure colors, unrelieved and uncontrasted, in large masses, but the brightest, strongest colors may be used with safety in units of sufficiently restricted size.  For harmony, as well as for richness, the law of complementaries, in its most general application, is the safest of all guides, but it must be followed with fine discrimination.  Complementary colors are like married pairs, if they find the right adjustment with one another they are happy—­that is, there is an effect of beauty—­but lacking such adjustment they are worse off together than apart.  Every artist who experiments in color soon finds out for himself that instead of using two colors directly complementary, it is better to “split” one of them, that is, use instead of one of them two others, which combined will yield the color in question.  For example, the color complementary to red is green-blue.  Now green-blue is equidistant between yellow-green and blue-violet, so if for red and blue-green; red, yellow-green and blue-violet be substituted the combination loses its obviousness and a certain harshness without losing anything of its brilliance, or without departing from the optical law involved.  Such a combination corresponds to a diminished triad in music.

Another important consideration with regard to color as employed by the architect dwells in those optical changes effected by distance and position:  the relative visibility of different colors and combinations of colors as the spectator recedes from them, and the environmental changes which colors undergo—­in bright sunlight, in shadow, against the sky, and with relation to backgrounds of different sorts.

The effect of distance is to make colors merge into one another, to lower the values, but not all equally.  Yellow loses itself first, tending toward white.  The effect of distance, in general, is to disintegrate and decompose, thus giving “vibration” as it is called.  A knowledge of these and kindred facts will save the architect from many disappointments and enable him to obtain wonderful chromatic effects by simple means.

Many architects unused to color problems design their ornament with very little thought about the colors which they propose to employ, making it an after-consideration; but the two things should be considered synchronously for the best final effect.  There is a cryptic saying that “color is at right angles to form,” that is, color is capable of making surfaces advance toward or recede from the eye, just as modelling does; and for this reason, if color is used, a great deal of modelling may be dispensed with.  If a receding color is used on a recessed plane, it deepens that plane unduly; while on the other hand if a color which refuses to recede—­like yellow for example—­is used where depth is wanted, the receding plane and