From
毛泽东《改造我们的学习》 (Mao Zedong, 'Reform Our Study,' 1941), quoting an old folk couplet about the 'subjective pedant':
墙上芦苇，头重脚轻根底浅；山间竹笋，嘴尖皮厚腹中空 (A reed on the wall: head heavy, feet light, shallow of root; a bamboo shoot in the hills: tip sharp, skin thick, hollow inside). Mao used it to attack formalist cadres who spouted theory without grasping Chinese reality. The couplet is attributed in folklore to Ming scholar
解缙 but became famous through Mao.
