不自量力 overestimate one's abilities
Explanation
不自量力，指过高地估计自己的能力，不考虑实际情况，盲目自信。这是一种缺乏自知之明，不切实际的行为。
Overestimating one's abilities, disregarding the actual situation, and being blindly confident. It is an unrealistic behavior lacking self-awareness.
Origin Story
春秋时期，一个小国名叫息国，国力薄弱，却一心想称霸中原。他们不顾自身实力，贸然对强大的楚国宣战。结果，息国军队兵败如山倒，损失惨重，最终被楚国灭亡。这便是历史上著名的“息国之败”，成为了不自量力的典型案例。息国国君的决策，体现了典型的轻敌冒进和不自量力的错误，导致国家灭亡。这个故事警示后人，做任何事情都要量力而行，切不可盲目自大，否则必将自食其果。
During the Spring and Autumn period, a small country named Xi, with weak national strength, wanted to dominate China. They declared war on the powerful Chu state without considering their own strength. Xi’s army was utterly defeated and suffered heavy losses, eventually being destroyed by Chu. This is the famous “Xi State defeat” in history, a classic example of overestimating one's capabilities. The ruler of Xi made the mistake of underestimating the enemy and being overly aggressive, leading to the demise of the nation. This story warns against blind overconfidence; always assess your strengths and weaknesses before acting.
Usage
用来形容人做事不量力，盲目自信，最终失败。
Used to describe someone who does something without considering their own abilities, blindly confident, and ultimately failing.
Examples
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他真是不自量力，竟然想一个人完成这个项目。
ta zhen shi bu zi liang li, jing ran xiang yi ge ren wan cheng zhe ge xiang mu
He really overestimated himself, trying to complete this project alone.
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小公司不自量力地挑战行业巨头，最终失败了。
xiao gong si bu zi liang li de tiao zhan hang ye ju tou, zui zhong shi bai le
The small company challenged the industry giant without measuring its strength, ultimately failing.