Snake-like Reflection of a Bow in the Cuping-bottom: 66.56%;">Nearly 2,000 years ago, during the Han Dynasty, there was a county magistrate called Ying Chen. One summer day, he invited his secretary Du Xuan to his house and treated him with wine. On the north wall of the room hung a red bow. It was reflected in Du Xuan's cup. Du Xuan took the reflection for a squirming snake. He was very frightened but he dared not turn down Ying Chen's offer because Ying was his superior. He had to swallow the wine with his eyes closed. When he was back at home he felt so painful in his chest and stomach that he could hardly eat and drink any more. He sent for the doctor and took some medicine, but nothing could cure him. When Ying Chen asked Du Xuan how he got so seriously ill, Du told him he drank the wine with a snake in his cup the other day. Ying Chen found something strange about that. He returned home , thought hard, but he could not find an answer. Suddenly the shadow thrown by the bow on the wall caught his eye. "That's it!" he shouted. He immediately sent his man to fetch Du Xuan. He seated him where he sat before and offered him a cup of wine. Du Xuan saw the snake-like shadow again. Before Du was scared out of his wits again, Ying Chen said , pointing at the shadow, "The 'snake' in the cup is nothing but a reflection of the bow on the wall!" Now that Do Xuan knew what it was, he felt much easier. And strange enough, his illness disappeared the next moment. This story was later contracted into the idiom "Bei Gong She Ying'. It is used to describe someone who is very suspicious. It is like saying someone is afraid of his own shadow. “杯弓蛇影”這則成語的意思是誤把映入酒杯中的弓影當成蛇。比喻因錯覺而疑神疑鬼，自已驚擾自已。 這個成語來源於東漢.應劭《風俗通義》，時北壁上有懸赤弩，照於杯，形如蛇。宣畏惡之，然不敢不飲。 有一年夏天，縣令應郴請主簿（辦理文書事務的官員）杜宣來飲酒。酒席設在廳堂裏，北牆上懸掛着一張紅色的弓。由於光線折射，酒杯中映入了弓的影子。杜宣看了，以爲是一條蛇在酒杯中蠕動，頓時冷汗涔涔。但縣令是他的上司，又是特地請他來飲酒的，不敢不飲，所以硬着頭皮喝了幾口。僕人再斟時，他藉故推卻，起身告辭走了。 回到家裏，杜宣越來越疑心剛纔飲下的是有蛇的酒，又感到隨酒入口的蛇在肚中蠕動，覺得胸腹部疼痛異常，難以忍受，吃飯、喝水都非常困難。 家裏人趕緊請大夫來診治。但他服了許多藥，病情還是不見好轉。 過了幾天，應郴有事到杜宣家中，問他怎麼會鬧病的，杜宣便講了那天飲酒時酒杯中有蛇的事。應郴安慰他幾句，就回家了。他坐在廳堂裏反覆回憶和思考，弄不明白杜宣酒杯裏怎麼會有蛇的。 突然，北牆上的那張紅色的弓引起了他的注意。他立即坐在那天杜宣坐的位置上，取來一杯酒，也放在原來的位置上。結果發現，酒杯中有弓的影子，不細細觀看，確實像是一條蛇在蠕動。 應郴馬上命人用馬車把杜宣接來，讓他坐在原位上，叫他仔細觀看酒杯裏的影子，並說：“你說的杯中的蛇，不過是牆上那張弓的倒影罷了，沒有其他什麼怪東西。現在你可以放心了！” 杜宣弄清原委後，疑慮立即消失，病也很快痊癒了。
