"A blessing in disguise is a blessing in disguise" is a famous saying?
It must be ... A blessing in disguise is an idiom from Huai Nan Zi Ren Xun. Metaphor may benefit from a temporary loss. It also means that bad things can be turned into good things under certain conditions. This fable in Huai Nan Zi Ren Xun is also called "a blessing in disguise".