A blessing in disguise is a blessing in disguise. How do you know the good and the bad? It is said that Sai Weng lost a horse, which he thought was a bad thing. The next day his horse came back with a batch of wild horses. His son tried to tame the wild horse, but he fell and broke his leg. But it was because of his broken leg that he didn't join the army, so he escaped the danger of being killed on the battlefield.