There is a harmony of lines, and this is even more difficult and complex to understand than harmony of color, for the harmony of lines reaches deeper than the harmony of color. If a room is beautifully furnished with costly furniture, but these things are not kept in harmony according to the science of lines, we feel a kind of confusion in the room. It is the same with clothes. A dress may be very costly or beautiful in color, but if it lacks line it lacks real beauty. Therefore in art line is the principal thing; it is the secret of art and of its charm, and only the artist who has conceived the beauty of line can express it in his art.