神机妙算 — “Brilliant foresight and ingenious planning”

In 208 AD, Cao Cao led a massive army south, intending to eliminate the forces of Liu Bei and Sun Quan and unify the land. Liu Bei dispatched Zhuge Liang to Eastern Wu to ally with Sun Quan against Cao Cao. Zhou Yu, the commander of Eastern Wu, was envious of Zhuge Liang's talent and constantly sought to get rid of him.

On one occasion, Zhuge Liang issued a military pledge, promising to produce 100,000 arrows within three days, or face execution. Zhou Yu was secretly pleased, believing Zhuge Liang could never complete the task, thus giving him an opportunity to eliminate him. However, Zhuge Liang had already devised a plan to accomplish the mission.

He secretly borrowed twenty swift boats from Lu Su, each fitted with over a thousand straw dummies. Early the next morning, under the cover of a dense fog on the river, Zhuge Liang ordered the straw boats to approach Cao Cao's naval camp, feigning an attack. This action perfectly embodies the meaning of 'Shen Ji Miao Suan'.

When Cao Cao saw this, he ordered his troops to shoot arrows at the perceived enemy. Instantly, over ten thousand archers from Cao Cao's army simultaneously fired arrows into the river. Before long, the straw dummies on the twenty boats were covered with arrows. Zhuge Liang then had the soldiers on the boats shout in unison, "Thank you, Prime Minister, for the arrows!" By the time Cao Cao realized what was happening, Zhuge Liang's straw boats had already sailed far away, leaving Cao Cao filled with deep regret.

Upon learning the details of Zhuge Liang's 'borrowing arrows with straw boats', Zhou Yu exclaimed with great emotion, "Zhuge Liang's ingenious mind has truly reached a miraculous level; I am indeed inferior to him!" This story is historically known as "Borrowing Arrows with Straw Boats" (草船借箭), and the idiom 'Shen Ji Miao Suan' is derived from it.