【解释】子：对别人的称呼；矛：进攻敌人的刺击武器；盾：保护自己挡住敌人刀箭的牌。比喻拿对方的观点、方法或言论来反驳对方。
【出处】《韩非子·难一》：“楚人有鬻楯与矛者，誉之曰：‘吾楯之坚，莫能陷也。’又誉其矛曰：‘吾矛之利，于物无不陷也。’或曰：‘以子之矛陷子之楯何如？’其人弗能应也。”
【示例】菲薄古书者，惟读过古书者最有力，这是的确的。因为他洞知弊病，能“～”。 ◎鲁迅《华盖集续编·古书与白话》
◎ 以子之矛，攻子之盾 yǐ zǐ zhī máo,gōng zǐ zhī dùn
[Turn sb's battery against himself;Fight sb.with his own weapon] 用你自己的矛来刺你自己的盾。比喻用对方的论点来驳斥对方
-----------------国语辞典比喻以对方的观点、理论来反驳对方。语本《韩非子．难一》：「楚人有鬻楯与矛者，誉之曰：『吾楯之坚，物莫能陷也。』又誉其矛曰：『吾矛之利，于物无不陷也。』或曰：『以子之矛，陷子之楯何如？其人弗能应也。』」
英语 lit. use sb's spear to attack his shield (idiom, derived from Han Feizi 韓非子|韩非子)?; turning a weapon against its owner, fig. to attack an opponent using his own devices, hoist with his own petard