Every cloud has a silver lining, next sentence.

The next sentence of "A blessing in disguise is a blessing in disguise" is "How do you know it is not a blessing".

An old frontiersman loses his horse—a blessing in disguise. From the sick jade edge: "A blessing in disguise is a blessing in disguise. You don't believe me at present, but you won't think I'm joking in the future. " Metaphor may benefit from a temporary loss.

Idiom story: An old man's horse in ancient Saibei ran to the Hu people outside the Great Wall. The villagers comforted him that this was not necessarily a bad thing. A few days later, the lost horse brought back some fierce horses. The old man thinks this is not necessarily a good thing. His son broke his leg riding, but the old man thought it was not a bad thing. Later, the old man's son escaped because of a leg injury.