Confucius, the founder of Confucianism and a thinker, politician, and renowned educator of the late Spring and Autumn period, is said to have had 3,000 disciples, over 70 of whom were distinguished. He taught his disciples to "be insatiable in learning," to combine learning with reflection, and never to slacken in their studies.
Among Confucius's disciples, Yan Hui received the highest praise from the Master, who considered him the most devoted to learning. Tragically, Yan Hui died young, leaving Confucius deeply grieved.
However, one of Confucius's disciples named Zai Yu was exceptionally lazy—he not only dozed off during lectures but often slept through the day. When Confucius learned of this, he was furious and declared, "Rotten wood cannot be carved, and a wall of dung cannot be plastered. For someone like Zai Yu, what point is there in reproach?" To Confucius, a student unwilling to improve and steeped in laziness was as hopeless as decayed timber or a filthy wall, making even criticism a waste of breath.
Confucius himself changed his approach to judging others after his experience with Zai Yu. Zai Yu had sworn solemnly to become Confucius's disciple, but once accepted, he grew habitually lazy. This led Confucius to remark, "In the past, when I heard a man's words, I trusted his actions. Now, when I hear a man's words, I must also observe his actions."
Fortunately, Zai Yu was deeply shaken upon learning of Confucius's criticism and disappointment. Filled with shame, he resolved to reform completely, transforming his "rotten wood" and "dung wall" image through concrete actions that earned Confucius's forgiveness. He studied diligently, progressed rapidly, and excelled in eloquence. Most notably, he possessed a valuable spirit of independent thinking, questioning Confucius's insistence on the "three-year mourning period." Later, his achievements led to his appointment as Grand Master of Qi's Linzi.
"Rotten wood" refers to decayed timber; "dung and dirt" means filthy mud. Later, the idiom "rotten wood and dung" came to describe useless things or hopeless individuals.
Source: *The Analects*, Chapter "Gongye Chang the Fifth"
Meaning of the Idiom: Later, the Chinese idiom "朽木粪土" came to describe useless things or hopeless individuals.