Ep18 summary: Jin Bu Yeon's final test for Nak Su … and she passsed.

More in-depth thoughts:
As of ep18, it does indeed appear Bu Yeon set things in motion. And she sealed Nak Su's power because she wants her to change.

Her isolation. Her witnessing the death of her father, and then later finding out she was used. Her being trained by Jin Moo's gang. Her being isolated. It made her in a fiercesome assassin because she lost her human connections and her humanity. She became a living weapon.

Bu Yeon want her to change. Bu Yeon chose her to take over her body.

Bu Yeon created the barrier as a final test for Nak Su. Now that she have human connections. Now that she is no longer alone. Which path would she choose? Back to being Nak Su the assassin, a name that is not even her birth name? Or, be Mu Deok?

I'm starting to think Bu Yeon even chose the name Mu Deok for Nak Su.

Mu Deok = 무덕 / 무덕이 it means:

  1. clear as mud (according to Naver)
  2. virtue (according to Google and Bing)
  3. Can also be written as 낙수 which means falling water. (According to Naver, Google, and Bing)
  4. According to Korean Wikipedia, one way of writing it in Hanja is 武德 which means military virtues.

The Hanja form is interesting. It means that it's meaning as "virtue" is not just any virtue but _military_ virtues. It does not fit Bu  Yeon, she is a Jin priestess. She was not trained to fight.

The meaning "clear as mud" is also interesting. It gives the idea of "tabula rasa" which means "blank slate". It is a theory that "individuals are born without built-in mental content, and therefore all knowledge comes from experience or perception".  (Wikipedia)

Bu Yeon did not choose the name "Mu Deok" for herself. She chose it for Nak Su.

Mu Deok is a new identity for someone who will be _reborn_. Someone given a "blank slate" (a new beginning) (tabula rasa) and regain knowledge from experience or perception.

It is "clear as mud". A mud that can be shaped into anything. A mud that can be molded into anything.

And with virtues. Not just any virtue but _military_ virtues. Trained to fight. Trained to kill. Have killed. But is connected to their humanity. That being trained as one is a responsibility.

Which even Master Lee sent the same message: if she will unsheathe Nak Su's sword then she will have to take responsibility. Master Lee figured out and understood why the "great power" inside Mu Deok's body is protecting her.

And it was also the last lesson of Bu Yeon to Nak Su when they finally were able to talk. Take one and you will lose another. It is a burden she has to take if she will use the ice stone.

Here's the kicker. I think that the ice stone barrier was not only to test Nak Su on which path she will take, I think it was also to teach her about the power of the ice stone and how to use it properly.

Noticed how they kept repeating and showing scenes about water, fire, and wind throughout the episode? Bu Yeon also told her "pull and get pushed" and how "overflowing power" means she will not be able to control how much of it she can use.

"Desire rain and you will get a flood."
"Desire wind and you will get a typhoon."

Choosing her path is not enough. She also has to learn to _respect_ the power of the ice stone and how to use it properly.

Through the barrier, Bu Yeon was able to give teach her the final lesson and let her realize the human connections she had made and make a decision based on it (instead of being "Nak Su").

Nak Su finally died and Astronomer Cho's daughter was finally reborn as Mu Deok.