Why did Shang Yang defend the spring war in autumn?

When Shang Yang (Wei Yang at this time, for convenience, Shang Yang) was still in Wei, Qin Wei had just finished the battle of Hexi. Although the outcome is even, Qin has been weak for a long time, and its national strength is empty, so it is impossible to fight again, otherwise it will be in danger of national subjugation.

Shang Yang suggested to Sun CuO, the prime minister at that time, that Qin adopted the strategy of fighting in spring and defending in autumn. He gave the following reasons:

1. Most of the soldiers' bodies and swords were injured in front of them, which shows that Qin people are brave. At this time, it was a life-and-death battle, and Wei could not destroy Qin in World War I;

2. Qin is poor, and the state treasury has no food, while Wei Guoqiang has sufficient reserves. Wei is also a prosperous trade center. Wei can use the war of attrition in the Spring and Autumn Period to kill the national strength of Qin.

It used to be the farming era, and the national strength mainly came from agricultural income. Sowing in spring and harvesting in autumn. If the state of Qin is attacked in spring, the Qin people will fight. Without time to sow, there will be no food to harvest in autumn and starvation in winter. On the contrary, Wei has strong reserves and trade. After a few years, Qin's national strength has been completely exhausted and collapsed without a fight!