To have the real knowledge of color and form is not easy for every artist. The sensibility for the minute shades of different colors and for the variety of shades in one color is a natural gift, which no study nor practice can teach, unless the artist is inspired by his own genius. It is difficult to have the feeling of the slight differences of thinness and thickness of the structure, and it is still more difficult for the average person to distinguish between the slight changes of color and form unless he is gifted by artistic insight. No doubt there is only one way of development, and if that way comes by itself so much the better.