侯门似海

hóu mén sì hǎi

lit. the gate of a noble house is like the sea (idiom)

fig. there is a wide gap between the nobility and the common people

hóu

marquis, second of the five orders of ancient Chinese nobility 五等爵位[wu3 deng3 jue2 wei4]

mén

gate

to seem

hǎi

ocean