Su Xun
The Six States of the East — Qi, Chu, Yan, Zhao, Han, and Wei — were all destroyed by Qin. Their destruction was not due to Qin's inherent strength, but because they themselves made sacrifices to Qin.
Qin's desire to annex the world and swallow up the Eight Wildernesses began with its acquisition of territory from the Six States. If the Six States had loved their people and treasured their land, and had not sacrificed territory to Qin, then Qin would not have been able to gain such power.
The states of Qi, Chu, Yan, Zhao, Han, and Wei each offered up land for different reasons. Han, Wei, and Chu served Qin out of fear; Qi and Zhao out of covetousness; and Yan out of anger. These are their different reasons.
Han, Wei, and Chu, seeing Qin grow stronger day by day and their own forces weakening, believed that by offering land and begging for peace, they could escape calamity. But the land of Qin was boundless, and its desire for land was insatiable. Each time they offered a foot of land, Qin demanded a yard; each time they offered a yard, Qin demanded a mile. The more they offered, the more Qin demanded, until all their land was gone. The moment their land was exhausted, their destruction followed. This is why Han, Wei, and Chu perished.
Qi and Zhao, seeing Han, Wei, and Chu being enfeebled by Qin, believed that by remaining neutral and refraining from assisting the others, they could preserve themselves. When Han, Wei, and Chu were on the verge of destruction, Qi and Zhao, instead of helping them, watched idly, even going so far as to send envoys to Qin to offer congratulations. But Qin's objective was to swallow the world. After destroying Han, Wei, and Chu, it would surely turn its attention to Qi and Zhao. When Qi and Zhao were on the verge of destruction, there were no longer any states left to help them. This is why Qi and Zhao perished.
Yan, after Jing Ke assassinated King Zheng of Qin, deeply offended Qin. Qin sent troops to attack Yan, and Yan perished. This is why Yan perished.
Thus, the destruction of the Six States was not due to Qin's strength, but because they offered land to Qin. The states that offered land perished. The states that did not offer land but stood by and watched others offer land also perished. The states that thought they were clever and managed to avoid directly confronting Qin also perished. Is there any difference in their ultimate fate?
If the Six States had loved their people and treasured their land, and had not offered up an inch of territory to Qin, but had instead united to resist Qin, they could have certainly preserved themselves. If they had fought Qin with their full strength, they would have probably been able to defeat Qin. Their land was more extensive than Qin's, and their population was greater than Qin's. When they offered land, their strength diminished with each offering. If they had used this diminished strength to fight Qin, they would have been unable to resist Qin's aggression. If they had not offered land, and had used their undiminished strength to resist Qin, then Qin would not have dared to invade.
This is why the Six States perished, not because Qin was strong, but because they offered land.