貪小失大

古時候，秦王帶領著大隊人馬去攻打蜀國，軍隊開到了蜀國的邊境，往遠處一看，不是一重重的大山，就是凹凸不平的山路，要想前進實在困難，而且也沒人知道怎樣的走法。

軍中有一個聰明的人，就想了一個法子來騙蜀國：他們用大石頭鑿成五隻大石牛，在石牛的後面故意放許多金子，告訴人家說這些牛的牛糞會變成金子。蜀王聽到這個消息，就命令很多年輕力壯的人，趕快開山鋪路，然後把五隻大石牛推回來。就在石牛一步步向回推的時候，秦國的軍隊也跟了上來，結果，石牛推回來了，蜀國也滅亡了。蜀王這才明白，自己貪了秦國這一點點金子，最後把國家亡了，實在不值得，但是後悔已經來不及了。

To Seek Small Gains But Incur Big Losses

In ancient times, the king of Ch'in once led his army to attack the kingdom of Shu. When the army reached the Shu border, however, they discovered that the terrain was all mountains, and the roads were full of bumps. No one could figure out how to get through.

Finally one of the soldiers thought of a way to trick Shu: the men took five large rocks and chisled them into cows. They then placed several gold pieces behind each cow, and told people that the cows' manure could turn into gold. When the king of Shu heard this, he sent many strong young men to go fix the road, and bring back the five cows. But as the cows were being pushed back, the Ch'in army was right behind them. And so, when the cows arrived, the kingdom of Shu was destroyed. At that point, the king of Shu realized that in seeking a little bit of Ch'in's gold, he had lost his entire kingdom. He thoroughly regretted having been so greedy, but it was already too late.

Thus, the idiom "To Seek Small Gains But Incur Big Losses" me ans to make a small profit but incur a great loss as a result.