Can someone explain: Stone white is like a fly, wood white is like a brush, and bamboo books should also have eight skills.

This sentence is a poem in Zhao Mengfu's "Xiu Shilin" in the Song Dynasty, which means that painting stones should be white, painting trees should have the brushwork of seal brush, and freehand painting of bamboo should be all eight methods. This sentence emphasizes that different painting elements need different brushwork and skills for better performance.