In the Warring States Period, there was a man in the State of Wei called Geng Lei. One day he said to the king: 'I can shoot down birds by simply plucking my bowstring.' When the king expressed doubt, Geng Lei pointed his bow at a wild goose flying in the sky, twanged the bowstring, and the goose fell to the ground. Geng Lei said, 'This goose has been hurt in the past. Hearing the twang of the bowstring, it assumed that it was doomed. So it simply gave up trying to live.
戰(zhàn)國(guó)時(shí)期（公元前403―221年中國(guó)中原地區(qū)各諸侯國(guó)連年?duì)帒?zhàn)的時(shí)代）魏國(guó)有個(gè)名叫更羸的人。一天，他對(duì)國(guó)王說(shuō)：“我只要拉開(kāi)弓，空射一下，就能把天上的鳥(niǎo)射下來(lái)?！眹?guó)王不相信。更羸便對(duì)準(zhǔn)天上飛來(lái)的一只雁射去，果真那只雁聽(tīng)到拉弦的聲音就掉了下來(lái)。國(guó)王感到很奇怪。更羸說(shuō)，“那是一只受過(guò)傷的雁。它一聽(tīng)到我拉開(kāi)弓弦的聲響，就驚慌得支持不住，自然要掉下來(lái)了?！?/div>

This idiom means that if one has been frightened in the past one's will may become paralysed in a similar situation.
“驚弓之鳥(niǎo)”這個(gè)成語(yǔ)比喻受過(guò)驚恐之后，有一點(diǎn)動(dòng)靜就特別害怕。