During the Warring States period, there were many strategists advocating for alliances, and Su Qin was one of the most famous.
To achieve the Vertical Alliance plan, Su Qin came to the State of Chu to persuade King Wei of Chu. Su Qin said:
Su Qin warned King Wei of Chu, "Chu is the mightiest kingdom under heaven, and you, Your Majesty, are one of the most talented rulers in the world. With a territory spanning five thousand li, a million soldiers, a thousand war chariots, ten thousand cavalry horses, and enough grain to last a decade, you have the capital to become a hegemon. With Chu's strength and your wisdom, you are invincible. Yet if Chu willingly serves Qin in the west, every other state will bow to Qin's rule. The harm Qin brings to the world is nothing compared to the threat it poses to Chu. When Chu is strong, Qin weakens; when Chu is weak, Qin grows strong—the two cannot coexist. Therefore, I advise you to unite with the other states in a vertical alliance, fostering friendship and isolating Qin. If you reject this path, Qin will soon attack in two prongs, and I fear the cities of Yan and Ying will be lost. I have heard that one must govern before chaos erupts and act before events unfold; once disaster strikes, regret is useless. I urge Your Majesty to decide quickly."
Seeing King Wei of Chu still hesitating, Su Qin pressed further: "If Your Majesty adopts my plan, I will order the eastern states to present their seasonal tributes to Chu, entrust their ancestral temples to your rule, and place their finest troops under your command. If you follow my humble strategy, the beautiful music and stunning women of Han, Wei, Qi, Yan, and Zhao will fill your harem, while the swift horses of Zhao and Dai will fill your stables. With the Vertical Alliance, Chu can become a true king; with the Horizontal Alliance, the King of Qin would become emperor. To abandon the path of a hegemon for the sake of serving others—I consider this unwise."
At that time, the Vertical Alliance and Horizontal Alliance factions were both fiercely active, each dispatching their most eloquent persuaders to lobby various states, with Chu being a prime target. Su Qin, anticipating this, pressed further: "Qin is a tiger-wolf state with ambitions to devour the world; it is the common enemy of us all. Those who advocate the Horizontal Alliance seek to carve up the lands of the feudal lords to serve Qin—this is truly nurturing an enemy and offering tribute to a foe. As ministers of their own states, they cut away their own territory to curry favor with a tiger-wolf Qin, harming the interests of all, heedless of the great disaster Qin will ultimately bring. Worse, they exploit Qin's might to intimidate their own sovereigns into ceding land, a treasonous act that exhausts all loyalty—nothing could be more heinous. Therefore, if you adopt the Vertical Alliance strategy, the feudal lords will cede land to serve Chu; if you adopt the Horizontal Alliance, Chu will cede land to serve Qin. These two policies are as different as heaven and earth, beyond calculation. Which will Your Majesty choose? Our King of Zhao has sent me to offer my humble counsel, present our clear pact, and await your decision."
For the state of Qin, King Wei of Chu had long been in a dilemma, having repeatedly weighed the conditions of the various feudal states. He listened very carefully to Su Qin's words. What worried him was that each state had its own agenda, making true unity difficult. At this point, King Wei of Chu had to state his position. So he said:
"Our state borders Qin to the west. Qin harbors ambitions to swallow Ba, Shu, and Hanzhong—truly a nation of tigers and wolves, impossible to befriend. Yet Han and Wei, pressed by Qin's threats, cannot be trusted with long-term plans; they might betray us to Qin, leaving our state in peril before any strategy is even discussed. I have judged that Chu alone cannot defeat Qin. Consulting my court officials offers no reliable support. Thus, I cannot sleep soundly nor eat with relish. My heart dangles like a banner in the wind, unable to steady itself or find a final mooring. Now, if your lord wishes to pacify the realm and the feudal lords, isolating our dangerous enemy, I will reverently entrust our altars of state to your command."
Later, "Heart Pennant Swaying" became an idiom, used to describe a restless mind, like a pennant fluttering in the wind, unsteady and unable to maintain composure.
Source: *Strategies of the Warring States*, Chapter "Strategies of Chu I"
Meaning of the Idiom: Later, the Chinese idiom "心旌摇曳" came to describe how a restless mind is like a pennant fluttering in the wind, unsteady and unable to maintain composure.