In the Warring States Period (zhàn guó 战国), there was a man in the State of
Wei (wèi guó 魏国) 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.'This idiom means that if one has been frightened
in the past ones will may become paralyzed in a similar situation.

战国时期(公元前403―221年中国中原地区各诸侯国连年争战的时代)魏国有个名叫更羸的人。一天，更赢和魏国国王在一个高台之上，仰望看见飞鸟，更赢对魏王说：“我可以为您表演拉空弓发虚箭但使鸟掉下来。”魏王说：“是吗，射箭的技术可以达到这种程度吗?”更赢说：“可以。”一会，有大雁从东边飞过来，更赢用虚发使(大雁)掉下来了。魏王说：“啊，射箭的技术可以达到这种程度啊?”更赢说：“这鸟是受过箭伤的。”魏王说：“先生你怎么知道呢?”回答说：“它飞得慢并且鸣叫的声音悲凉。飞得慢的原因，是有旧伤，鸣叫悲凉的原因，是离群的时间很长了。老伤没好那么惊惧的心就没过去。听到弓弦的声音，努力舞动翅膀往高处飞，老伤发作就掉下来了。”

惊弓之鸟

【翻译】 1.A bird startled by the mere twang of a bow-string.

2.A badly frightened person; a panic-stricken person.