An art student was learning under a master artist for some years. His drawing was good in the sense of representation. But he wasn't satisfied with whatever he drew.
When this restlessness became unbearable, he ended up asking his teacher about it.
The teacher was glad that the child was about to learn something significant. "Unless you know the simplicity of line, all that you do as art will be mere decoration. Work on the line, the rest will follow", said the teacher.