From this little experiment we may conclude that a warm light provokes a cold shadow, a cold light a warm shadow, and that the color of the shadow is complementary to that of the light. In the experiment, daylight was the source of the cold light. Let us now take a third source of light, warmer than that of the candle, the flame produced by burning alcohol and salt--a very warm, deep orange light, which makes the light of the candle seem cold and its blue shadows appear yellow, while its own shadows are blue. We recently observed a very striking example of these warm and cold appearances of light; it was at the theater: a beam of red light shone brightly upon an actor, whose shadow was absolutely green. Some of the people around us were astonished at the phenomenon, which they could perceive very plainly. Phenomena of this kind are produced every instant in a nature illuminated by the sun; nearly all the shadows are colored in hues which we can distinguish with a little attention where the unpracticed eye sees nothing but gray. Thus in a mountainous country, exposed to the warm light of the sun, the mountains in the horizon appear blue through the haze; then, as evening draws on, the sun appears a deeper orange, more reddish, while the sky seems green by contrast, and the red rays of the sun falling on the mountains turn them violet, in those beautiful tints which give so much glory to those countries of large shadows and bright lights. However intense the light of day may be, it is therefore always colored, and gives those colored shadows which painters do not always observe. The painter, in fact, should make an analysis of the complex light around him, and should repeat the result in synthesis on his canvas. Upon hardly any other condition can he represent the transparency of the atmosphere, or the luminosity of a subject or a landscape. These colored shadows are not, therefore, false colors, as often seems to be believed, or optical illusions; they are really existent, but our eyes are hardly ever practiced enough to discern them; we are deficient in education of the color sense. This education is not hard to attain. There are persons who have special aptitudes and are consequently remarkable colorists, just as some persons have an admirably organized ear for music; but, besides these, it is possible for all persons endowed with the faculty of observing and capable of attention to acquire with considerable rapidity the faculty of discerning colors, where they at present hardly see anything but confused gray masses. (The epithet gray, we may observe, is used as applied to many things the color of which is not susceptible of exact determination.) Such attentive observation of colors is, however, attended with some danger to painters. Every person prefers some one color, is influenced by a particular shade. When we examine the works of the painters we see that there are many differences in the way of seeing.