Color and mass are the painter's medium, his language. The final import of art is the _idea,_ the emotional content of the work. On his way to the expression of his idea the artist avails himself of material to give his feeling concrete actuality and visible or audible realization. He paints a picture, glorious in color and compelling in the concentration of its massing; he carves a statue, noble in form or subtly rhythmic; he weaves a pattern of harmonious sounds. He values objects not for their own sake but for the energies they possess,--their power to rouse his whole being into heightened activity. And they have this power by virtue of their material qualities, as color and form or sound. A landscape is gay in springtime or sad in autumn. The difference in its effect upon us is not due to our knowledge that it is spring or autumn and our consciousness of the associations appropriate to each season. The emotional quality of the scene is largely a matter of its color. Let the spring landscape be shrouded in gray mist sifting down out of gray skies, and we are sad. Let the autumn fields and woodland sparkle and dance in the crisp golden sunlight, and our blood dances with them and we want to shout from full lungs. In music the major key wakens a different emotion from the minor. The note of a violin is virgin in quality; the voice of the 'cello is the voice of experience. The distinctive emotional value of each instrument inheres in the character of its sound. These qualities of objects art uses as its language.