侯门似海

Explanation: The doors to the nobility as Shensui like the sea. Old wealthy nobles, the officials of the heavily fortified, and most people can not easily enter. Also be used to old acquaintances, due to the status of the poor and alienated. 　　Source: Cui Tang Country, "presented to the servant," son of the Sun-by footsteps, green bead drops Tears Romania; Hou door into the deep as the sea, from Xiao Lang is a passer. " Thesaurus:  Once inside the marquis' door there's no turning back (said of sea