I had a strange experience with a guy who insisted that everything my teachers have been teaching me for years about energy work in the martial art, my art is of course - Taiji quan, is wrong.
After the experience I felt I really do not know how to talk about Jing, which simply translates to energy.
I would like to get some opinions on how to talk about Jing, or what is Jing from some other points of view.
-smiles-
At this point I am not entirely sure which Jin. I’m sorry, I understand only the mainland Chinese romanization. I will spell it jin4. The Chinese character 勁 did help alot though. I have a tendency to not here the difference between final sounds like -in and -ing. 
As a result, I am not really sure if the arguement was about 勁, jin4, or 精, jing1. In any case, I have done some reading, and created this poem to help me understand. Go ahead and give me your opinion. It seems to agree with the 勁 definition you gave me.
一起聯合變為太極 Together they flow creating Taiji.
精為陰 Jing represents Yin.
氣為陽 Qi represents Yang.
精為無 Jing represents emptiness.
氣為有 Qi represents abundance.
精為無力 Jing represent absence of strength.
氣為有力 Qi represents abundance of strength.
I would agree with Juba that it is jin 勁, which I have always translated as just “power.” I’m at work now, but at home I have a couple of good books that talk about this subject in great detail. The author is mostly a lot of hype, but there is some useful information in there. I’ll post the info later tonight when I get home.
I was hoping someone would bring up this topic, as I’m still working out the meaning of energy.
The Indonesian martial art I’ve been studying (which has elements of Shaolin Kung Fu) teaches in terms of 3 priciples: physical, mental and spiritual. It’s often a little hard to differentiate one from the other, and to be honest, I’m not worried about trying to differentiate… Anyway, various forms of “energy” are taught, ranging from something like an internal strength or power (which is used for striking, blocking or deflecting force), to another that is more like a “sense” (but which can also be used in a similar manner to the internal strength). My definition of the latter is still a little vague because I haven’t yet been taught this principle, but I believe it is very spiritual (although there could also be a 3rd, spiritual type of energy that I haven’t yet been taught). A number of Grand Masters have been known to use their energy to heal sick or injured people and to hurt those who have attacked them - without actually touching them - and these guys sometimes observe the so-called faith healers who travel from village to village throughout southeast Asia.
A lot of this defies western science, but I do believe that through intensive physical and mental training over a prolonged period of time, one can learn to use energy in a way that western science can’t explain. Unfortunately, thanks to my current lifestyle, I’m probably a long way from reaching such a level! Might have to watch another episode of Tommy Boy…
While writing the poem I talked to my wife about the subject. The concept of Jing (精), Qi (氣), Shen (神) seem to be common knowledge to the Taiwan people. She agrees with the concept that Qi leads to power (力). Li (力) is related (勁) I believe, as in the term Fa Jin (發勁) - delivering explosive energy. Jing seems to be essence, Qi is differicult to translate other than calling it air, while Shen seems to be spirit. Some of my martial arts teachers have talked about developing Jing and Qi in order to improve Shen. I am not clear on this, however.
My current training is using Jing as a lack of energy or power, while Qi is being used to deliver direct force, Jin, after Jing has been established. My scientificaly minded student does not yet understand how I am using relaxation from so called Jing to destabilize him, and I admit that I am learning to understand it myself. I do not understand concepts, yet, like how to change Jing into Qi - Power. Although power alone is easy to understand.
So what is Shen?
I’ve been given hundread of different answers to Jing, Qi, Shen.
But as I understand it at this moment (could change by the time I finish my post).
Shen is the philosphy of the art you are studying. Every school has a philosophy unique to the style. To master a style you must be in the shen. Like the animal style…“be the praying mantis” is the shen.
Qi is really in western sense is cardio vascular training. It is learning breath control for relaxiation and for sparring. If one is to master the soft and hard of a style, one needs to learn the breathing techniques to be most effective. Simple forms of this Qi in martial art are expressed with lots of yelling while finishing a technique.
Jing is basically muscle and tendon training in western sense. If you have the Shen and Qi, without proper Jing, you’ll get hurt and end up in the hospital, trying to example how you hyper-extended your groin.
Alot of this stuff is based on Chinese medicine and philosophy which is as logical and scientific as Taipei traffic patterns.