Gu Rong of the Eastern Wu in the Three Kingdoms period was exceptionally perceptive and often saw through issues with great clarity. After the fall of Eastern Wu, he went to Luoyang with the brothers Lu Ji and Lu Yun, and all three gained high renown, being called the "Three Talents" by their contemporaries.
During the turbulent final years of the Western Jin Dynasty, the scholar-official Gu Rong served under several princes—Prince Zhao of Zhao, Prince Qi of Qi, and Prince Changsha of Changsha—but fearing the chaos would engulf him, he resigned and fled south to the Jiangnan region. Soon after, the Guangling chancellor Chen Min rebelled, driving out the court-appointed officials and placing his own clansmen in charge of the commanderies, while recruiting heroes from across the land in a bid to carve out his own kingdom east of the Yangtze, much like Sun Quan had done centuries earlier. Recognizing Gu Rong's prestige, Chen Min appointed him as Right General and Administrator of Danyang.
Gu Rong secretly said to Gan Zhuo, who commanded the main army, "Chen Min has only mediocre talent, and his sons and brothers are arrogant and complacent. They cannot achieve great things. Let us find another way."
The following year, Gu Rong joined forces with Gan Zhuo and Ji Zhan to launch an attack on Chen Min. Gu Rong destroyed the bridge outside the city, cutting off Chen Min's escape route, and waving a feather fan to direct his troops, he defeated Chen Min's forces.
Gu Rong rendered great service to the Jin Dynasty. After his death, Yin You, the governor of Wu Commandery, petitioned the emperor, stating, "When Chen Min rebelled, the entire court was at a loss for a plan. Only Gu Rong, amidst great danger, secretly united trusted allies to suppress the rebels, causing the rebel forces to collapse. From ancient times to the present, no one's merit has ever been as great as his." He requested the emperor to grant Gu Rong posthumous honors. The emperor issued an edict, bestowing upon Gu Rong the titles of Imperial Advisor and General of the Flying Cavalry, with the posthumous name "Yuan."
Later, the idiom "At Wit's End" came to describe having no solution in mind.
Source: *Book of Jin*, "Biography of Gu Rong"
Meaning of the Idiom: Later, the Chinese idiom "计无所出" came to describe how having no solution in mind.