Taijiquan is to a large extent restraining our physical activity in every move. That is the purpose.
Taijiquan is an invention of Taoist. From the eyes of a Taoist, the nature is a combination of ying and yang. That is Tao. Most of our day to day live, we are moving our body actively. There is little time to contemplate the role of our mind in administering the body's movement. It symbolizes yang. While we practice Taijiquan, we become more aware of the presence of mind and actually using the mind to move the arm and leg. This is a reverse in order of precedence. It symbolizes ying. This is a macro view of the purpose of Taijiquan, playing a part in the balancing of ying and yang. Many find its value in rejuvenating our body, or health value.
Whereas the micro view is that, it offers us an opportunity to be serious about the presence of our mind. In this case, physical body is yang, and mind is ying. They should be given the same emphasis in importance. Its the first step, being the preparation for the more advance practice.
Followingly, the practice is to train that the mind would become powerful enough to take charge, and able to move the body, arm and leg. This is the frist time our mind become the more predominant issue in our live. The presence of mind power is confirmed at this time. It is as if the mind has bcome yang, and body has become ying.
We may also think that practicing Taijiquan is similar to meditation in that, the conventional meditation is we sit on the floor or buttocks. Whereas practicing Taijiquan is sitting on our thigh or leg. Initially the Taoist worried that sitting to long on the floor would stiffen our body, which is one of the purposes of inventing the Taijiquan.
What is meditation? Most of us think that meditation is to lay back and do nothing, and empty our mind and worry. Then coming out from meditation is like coming out from sleep. Far from it! Meditation is to a large part strenuous in mind manipulating and breadth manipulating. Likewise, practicing Taijiquan is equally strenuous.
What is the purpose of all this? Now we are coming to the more advance step.
Remember seeing the Taiji Diagram? Which has a black portion at one side, and white portion at another, and with black dot in the white portion and white dot in the black portion. I am going to illustrate the mystery in the light of physics and engineering.
The black and white dot may be imagined as the electrodes with positive charge at one and negatice charge at another. The black mass patch may be imagined as the elements with positive charges, and the white mass patch as the elements with negative charges. We know that the mass with positive charge will be attracted to the electrode with negative charge, and the mass with negative charge will be attracted by the other electrode. Hence the spinning motion is resulted.
However, the moment the mass with positive charge arrives at the electrode with negative charge, the spinning motion may come to a halt. THE MAGIC IS, TO KEEP ON ALTERNATING THE CHARGE AT THE ELECTRODE! Like the electrical generator is doing. And the spinning motion would continue.
The other important point is the spinning motion is not just on a 2 dimensional plain. It is coupled with a another movement which is perpendicular to the plain. Either the movement is drilling out from the plain or drilling in depending on the spinning being clockwise or anticlockwise. In electrical engineering, it is the fundamental theory of creating electrical current using magnet and wire coil.
Where does qi come from? From the drilling motion of charged elements. Thus, to create qi, one has to be able to spin the ying and yang. To spin the ying and yang, one has to be able to create alternated charges at the very same electrode. The electrodes are the conceptual mind. In meditation, we train ourseleves to make real the imaginary, and to see real as an illusion. Step 1: to see mountain as mountain, to see water as water; step 2: to see mountain as not mountain, to see water as not water; step 3: to repeat step 1 & step 2..........
The speed of qi moving is relative to the frequency of the conceptual mind alternating, which pulls the charged mass. The moment the alternating is so extreme that the conceptual mind can no longer differentiate the real and the illusion, that is when the speed of qi approaches the speed of light. That is when the mind transcends space-time dimensions. Or simply, the state of enlightenment.
Do you notice the cross like figure in Buddhism similar to the symbol of Nazism? That thing actually spins. Therefore both Buddhism and Taoism share the same spinning theory. Taoism is slightly more discreet by actually naming the ying and yang. What is nirvana? It is the whole of the spinning zone. The centre of the spinning zone is called the absolute nirvana. That is where everything turning into singularity.
"jing, qi, shen, shi" Jing is the mass of elements with charges, qi is the elements started spinning and drilling with motion, shen is the transcended mind when ying and yang merged, and shi is the centre of the spinning zone, where the absolute nirvana resides.