sài wēng shī mǎ yān zhī fēi fú
the old man lost his mare, but it all turned out for the best (idiom); fig. a blessing in disguise
it's an ill wind that blows nobody any good
yàn què yān zhī hóng gǔ zhī zhì
lit. can the sparrow and swallow know the will of the great swan? (idiom); fig. how can we small fry predict the ambitions of the great?
yān zhī
(literary) how is one to know?