The media of pictorial expression are color and line, and expression is attained through them in a twofold fashion. In a picture, every element of color or line is expressive directly, just as color and line, of some vague feeling or mood, and, in addition, chiefly through its resemblance, represents some action or object. The former kind of expression is indispensable. No matter how realistic the imitation, unless the picture thrill like music, through its mere colors or lines, it is aesthetically relatively ineffective. It is not sufficient that the picture move us through the vicarious presence on the canvas of a moving object; it must stir us in a more immediate fashion through the direct appeal of sense. For example, a picture which presents us with a semblance of the sea will hold us through the power which the sea has over us; but it will not hold us so fast as a picture of the same subject which, in addition, grips us through its greens and blues and wavy lines. The one sways us only through the imagination, the other through our senses as well. Sensitiveness to color as such, so self-evident to one who possesses it, seems to be wanting, except in rudimentary fashion, in a great many people. They are probably few, however, who do not feel some stirrings when they look through the stained glass of a cathedral window or upon the red of Venetian glass, or who are entirely indifferent to the color of silk. The reason for emotional color-blindness is probably not a native incapacity to be affected, but rather a diversion of attention; color has come to be only a sign for the recognition and subsequent use of things, a signal for a practical or intellectual reaction. In our haste to recognize and use we fail to see, and give ourselves no time to be moved by mere seeing. But when, as in art, contemplation, the filling of the mind with the object, is the aim, the power to move of the sensuous surface of things may come again into its rights.