According to Song Zengminxing's "Awakening alone magazine":
Dongpo said: "Although Lu Zhi (the figure of Huang Tingjian) is bright and vigorous, his brushwork is sometimes too thin, like a snake hanging from the treetop." The valley said: "The word' Gong' can't be underestimated, but suddenly it feels shallow, just like killing a toad with a stone." The second man smiled and thought he was very ill.