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 the approaching color neutralize one another, resulting in an effect of flatness not intended. The tyro should not complicate his problem by combining color with high relief modelling, bringing inevitably in the element of light and shade. He should leave that for older hands and concern himself rather with flat or nearly flat surfaces, using his modelling much as the worker in cloisonné uses his little rims of brass--to confine and define each color within its own allotted area. Then, as he gains experience, he may gradually enrich his pattern by the addition of the element of light and shade, should he so decide.