pretty good but

If you left the theater with a tight chest, this movie has done its job. It successfully conveyed the desperate feeling from a educated woman when facing the social structure. It's unfair; it's killing; she fought; but she lost, because there is no way that she could win. If this fouth mistress finally rescued the third and killed the second (the evil woman) and then left the master, that would be a Hollywood movie again.

The lesson is simple. Don't quit the university after just six months.

does a movie require a lesson to be transposed?

all i can say is this movie is well ahead of its time. its script is not as straight forward as it seems if one would look through the layers. also of its derogatory literature which made it forbidden in China for a period of time. this is film noir at its best.

Since when must a movie have a "message"?

In life, meaning is "created," imputed to neutral reality.