Having become convinced of this power of light, the lighting expert may turn to artificial light, which is so easily controlled in direction, distribution, and color, and draw upon its potentiality. Not only is it easy to provide a lighting suitable to the mood or to the function of an interior but it is possible to obtain some variety in effect so that the lighting may always suit the occasion. A study of nature's lighting reveals one great principle, namely, variety. Mankind demands variety in most of his activities. Work is varied and alternated with recreation. Meals are not always the same. Clothing, decorations, and furnishings are relieved of monotony. One of the most potent features of artificial light is the ease with which variety may be obtained. In obtaining relief from the monotony of decorations and furnishings, considerable expense and inconvenience are inevitably encountered. With an adequate supply of outlets, circuits, and controls a wide variety of lighting effects may be obtained with perhaps an insignificant increase in the initial investment. Variety is the spice of lighting as well as of life. These various principles of lighting are readily exemplified in the lighting of the home, which is discussed in another chapter. The church is even a better example of the expressive possibilities of lighting. The architectural features are generally of a certain period and first of all it is essential to harmonize the lighting effect with that of the architectural and decorative scheme. Obviously, the dark-stained ceiling of a certain type of church would not be flooded with light. The fact that it is made dark by staining precludes such a procedure in lighting. The characteristics of creeds are distinctly different and these are to some extent exemplified by the lines of the architecture of their churches. In the same way the lighting effect may be harmonized with the creed and the spirit of the interior. The lighting may always be dignified, impressive, and congruous. Few churches are properly lighted with a high intensity of illumination; moderate lighting is more appropriate, for it is conducive to the spirit of worship. In some creeds a dominant note is extreme penitence and severity. The architecture may possess harsh outlines, and this severity or extreme solemnity may be expressed in lighting by harsher contrasts, although this does not mean that the lighting must be glaring. On the other hand, in a certain modern creed the dominant note appears to be cheerfulness. The spacious interiors of the churches of this creed are lacking in severe lines and the walls and ceilings are highly reflecting. Adequate illumination by means of diffused light without the production of severe contrasts expresses the creed, modernity, and enlightenment. On the altar of certain churches the expressiveness of light is utilized in the ceremonial uses which vary with the creed. Even the symbolism of color