This is why in Song art we see bamboos painted in black ink. The bamboos 'green color exists only briefly, so painting them in ink became an artistic metaphor: the artist was capturing a concept, not external form, so its nature was more pure.
所以宋畫中出現了墨竹，竹子的綠色既是短暫的存在，不如用墨色來畫，成為繪畫上的一個比喻，抓住的是理念而不是外型，所以本質更純粹。