Intimate details of Chinese life behind walls as only this writer can give.
Again, if I remember the title to story correspondence correctly, this is about the growth of awareness of a woman after she is forty and has decided to not be embarrassed with another child any more as she has seen some of her friends are - and since this is before the contraceptives, there is only one way; she declares her intention to her husband while providing him with another, younger wife.
This is the beginning of the story.
The husband is baffled but unable to do anything but comply - he loves his forty something wife, but cannot yet be ready to renounce physical needs, and the new woman is young, though he misses his more intelligent wife in intimacy.
The wife meanwhile interacts with the European priest who comes as a tutor to her son, and learns while sitting in on the sessions, and marvels at her previous lack of awareness about the world.
Incidentally this story brings the startling - for Europhiles - discovery that the orientals think of Europeans as physically ugly, unattractive, and ridiculous.
Startling, because generally conquerors take it for granted that they are superior in any and every way - including physical attraction. And Europe having been the more recent colonising conquerors, there was generally no one to tell them otherwise.
But then again when Mongols conquered practically half the world, they thought the same about themselves, too.