圬木不可雕也

出处《论语·公冶长》 

宰予昼寝。子曰：“朽木不可雕也，粪土之墙不可污也。”  

释义:这个成语也称“朽木粪土，比喻人已经败坏到不可救药的地步。  

故事:孔子的弟子宰予，言辞美好，说起话来娓娓动听。起初，孔子很喜欢这个弟子，以为他一定很有出息。可是不久，宰子暴露出懒 惰的毛病。 一天，孔子给弟子讲课，发现宰予没有来听课，就派弟子去找。 一会儿，去找的弟子回来报告说，宰予在房里睡大觉。 孔子听了伤感他说： “腐烂的木头不能雕刻，粪土一样的墙壁不能粉刷。最初我听到别人的话，就相信他的行为一定与他说的一样；现在我听别人的话后，要考察一下他的行为。就从宰予起，我改变了态度。” 

This is basically a famous proverb by Confucius. Upon getting disappointed by one of his favorite  student, he made the comment of ," Rotten logs aren't suitable for craving, walls that are like waste matter can't be painted". In short it's use to describe cases of hopelessness. As a continuation of my views on Alain de Botton's TED talk, personally i think if someone (who is not doing very well) do not blame themselves for their fault, if someone thinks he/she is born to behave a certain way and only chose to listen to the good things people comment about, then they are as good as hopeless.