Geng Lei was strolling with King Wei when they saw a wild goose flying in the distance. He said to King Wei, "I can make that bird fall without using an arrow, just by twanging the bowstring." King Wei listened, shrugging with a smile, "Your archery skills are that extraordinary?" Geng Lei confidently replied, "Yes."

A moment later, the goose flew directly overhead. Geng Lei drew his bow, and with a 'bong' sound from the bowstring, the goose first shot upwards fiercely, then flapped its wings feebly in the air a few times before plummeting to the ground.

King Wei was so astonished he couldn't close his mouth for a long time, clapping his hands and exclaiming, "Oh, to think archery could be so superb, truly unexpected!"

Geng Lei said, "It's not my superb archery, but because this wild goose already had a hidden injury." King Wei was even more puzzled, "The goose was so far away, how could you know it had a hidden injury?"

Geng Lei explained, "This wild goose was flying very slowly, and its cry was mournful. Based on my experience, flying slowly indicates an internal injury, and a mournful cry suggests it has been separated from its flock for a long time. This lone goose, with its old wounds unhealed and still in a state of alarm, was so terrified by the sharp sound of the bowstring that it tried to flee by flying high. Due to flapping its wings too vigorously and using excessive force, its old wound reopened, causing it to fall."