A. The root of Complementary
The yin and yang complementary concept means that when there is no yin, there will be no yang. If there is no yang, there will be no yin. Yin came from yang and yang came from yin. Yin or yang by itself cannot survive.

B. The Root of Opposites
The yin and yang opposite concept means that these two components are opposite of each other to demonstrate their existence and they will constantly struggle or position themselves to be on the upper end. This is the basic nature of all things in motion.

C. The Root of Balance
The yin and yang balance concept means that because the two components are constantly postioning themselves, there will be a temporary balance. This temporary balance is the result of yin and yang controlling each other.

2. Tai Chi Symbol
A Tai chi symbol is a circle divided into two components known as yin and yang. The circle is referred to as Tai Chi or the universe. The black and white components are the yin and yang components or yin and yang figures. The black component has a white dot - meaning there is a yang in the yin. The white component has a black dot - meaning there is a yin in the yang. This demonstrates that it is the nature of everything that there are opposites and complementary things. The separation line of the two components is in the shape of an S. This causes the yin and yang figures to transform from and into each other.

3. Yin and Yang in Tai Chi Chuan
The Tai Chi Chuan Classics say that Tai Chi came from Wu Chi. When it is in active form, it is divided into two. When it is in an inactive form, it comes together. From the Tai Chi symbol, we see that Tai Chi Chuan is an active form. Therefore, we should expect to see yin and yang exist everywhere in the solo form. The yin and yang components of Tai Chi Chuan practice can be interpreted into hard and soft interaction, fast and slow movement, extension and contraction of the muscles, coordination of top and bottom, harmony of inside and outside, open and close motion, empty and full of the body's weight, advance and retreat of the stepping, left and right motion of the eyes and active and inactive of the mind.

A. Empty and Full
It is very important in Tai Chi Chuan practice to be able to understand the empty and full concept. Generally, in Tai Chi Chuan practice, empty refers to the top and full refers to the bootm. Here, top refers to the upper body. The upper body is very light, as if empty. Bottom refers to the lower body. When the feet are full, it forms a strong foundation. Therefore, empty the top means suspend the head from above, relax the shoulders and sink the elbows, relax the chest and raise the back, loosen the waist and pull the abdomen inward. Full in the bottom means to pull the buttock inward, open the groin, bend the knees and point the toes forward.

The bottom has to be full in order to be stable. The top has to be empty so that it will be easy to move. This empty and full happens everywhere in the body. After one understands this concept, the body will have a better balance and coordination.

B. Hard and Soft
Tai Chi Chuan appears to be all soft because one only sees the softness and not the hardness in the Tai Chi Chuan Solo Form practice. This leads many people to believe that this is how Tai Chi Chaun works. In Tai Chi Chuan practice, relax, empty and soft are close relatives. Tension, full and hard are also close relatives. They are very similar and yet there is something that keeps them apart. Rleaxation and tension are internal Fundamental principles. Empty and full function based on this fundamental principle. Hard and soft is the external expression of relaxation and tension, empty and full. This hard and soft concept should not be understood as "hardness" like rock and "softness" like water, rather, one should understand it as the result of relaxation or one should understand it in relationship to flesh and bone of the human body. Therefore, one should understand hard as concentrated and stable, soft as lightness and nimble. It is a result of total body relaxation and coordination. This is why many instructors ask their students to perform Tai Chi Chuan in a relaxed, soft and slow way. The truth is that when there is lightness, there is balance. When there is soft, there is hardness. If there is no concentration and balance, there cannot be lightness and nimbleness.

C. Fast and Slow
In Tai Chi Chuan, the movements are done slowly for the following reasons:

1. To obtain total body relaxation and proper muscle contraction
2. To master the circular motion
3. To concentrate on all the yin and yang elements
4. Self-examination of all the movements
5. To develop coninuity
6. To maintain normal breathing pattern
7. To maintain internal communication:
   1. Proper functioning
   2. Harmonize the nervous system
   3. Acknowledge the Chi and blood Circulations
8. Eliminate waste of excess energy
9. Emphasize the importance of body movements over four limbs

D. Open and Close
In Tai Chi Chuan, every movement has an open and close motions. Open is expanding from inside to outside. Close is contracting from outside to inside. Therefore, open and close is also known as extension and contraction. Tai Chi Chuan practice is the motion of opening and closing and vice versa. When it is open, it is large and expansive and there is no more space outside. When it is close, it is so compact and tight there is no more space inside. For a beginner, the open motion should be bigger so that there is more stretching on the muscles, ligament and tendons. For an experienced practitioner, the open motion should be smaller and among each open and close motion, there is a subdivision into smaller open and close motions.

This is what Yang Cheng Fu meant when he said that first one should practice extension form and later compact form.

E. Top and Bottom, Left and Right, Front and Back
These three -- top and bottom, left and right, front and back -- are very common. Each movement must take care of the opposite side. When one is doing the left side, one must be aware of the right side. When one is doing the top, one must be aware of the bottom. When one is doing the front, one must be aware of the back. There should be a coordination of the opposites so that the body will move as a unit, the parts should respond to each other and the body parts should communicate with one another.

F. Relaxation and Tension
Relaxation is the most basic of Tai Chi Chuan practice. It requires the whole body to relax during activity. From the brain, the nervouss system, muscle groups, ligaments,tendons,joints, conneective tissues and organs. When the body is relaxed, the mind is calm, clear and focused. The yin and yang theory explains that one cannot survive without the opposite. Although the Tai Chi Chuan practitioner does nt talk about tension as we know it, tension in Tai Chi Chuan is defined as twisting and stretching of the body, arms and legs. From this tension and relaxtion or twisting and stretching, extra exercise goes to the body's joints, muscles, the nervous system and internal organs as suggested in yin and yang. Relaxation and tension support each other. The more one can relax, the more one is able to twist and stretch. The more one is able to stretch and twist, the more one can relax. This why the body is nimble and the mind is clear calm and concentrated. Throughout the Tai Chi Chuan Solo Form, we see the upper body is relaxed and the lower body is full of tension. When one performs the kicking, the standing leg does not relax. When the hands close into a fist, the muscles, the shoulder and elbows relax. Most people who practice Tai Chi Chuan emphasize more on relaxation than tension because tension occurs more in life. When we are excited about something or when we step into a new environment, our body automatically tenses. Practicing Tai Chi Chuan regularly can remove this tension. This is why Tai Chi Chuan is so popular today as a form of stress management technique, a perfect medicine for today's stressful society.

G. Active and Inactive
In Tai Chi Chuan, tranquility comes from the active. The Tai Chi Chuan Classics say to look for tranquility in action or tranquility during activity. Seeking tranquility from activity is a yin and yang concept of excitation and depression. We know that absolute depression and absolute tranquility do not exist.

Applying the consciousness to quiet the excitation is a very difficult task, especially since we are living in a society where temptations exist everywhere. This is why in ancient China, Taoists lived in isolation to remove themselves from temptations. The more one removes from these temptations, the more they appear. Tai Chi Chuan practices is but one of many techniques to achieve the internal condition of tranquility as the result of external behavior. This is achieved for the practitioner by focusing on one behavior or stimulant and screen out all others. Therefore, in order to develop a mental tranquility by practice the physical Tai Chi Chuan's movement, the movement should be light, relaxed and smooth.

H. Inside and Outside
The Tai Chi Chuan Solo Form is the physical interpretation of Tai Chi philosophy. It is governed by the external three harmony. When the body relaxes, it will be calm and tune the nervous system. When the nervous system is relaxed, it will better regulate and communicate with the body's organs and functions so that the whole body can be relaxed and in a better health. This is what Yang Cheng-Fu meant when he said that inside must be coordinated with outside in order to advance in Tai Chi Chuan skill.

Now, we see that Yin and Yang does not refer to one thing. It simply refers to things that exists in duality, although in our society yin and yang are recognized as opposite of each other. This is but a tool to distinguish one's existence. We must recognize the complementary concept. From this Yin and Yang interaction, many things can and will happen. In order for one to advance in Tai Chi Chuan skills, one must understand Yin and Yang definitions as described above and apply them to Tai Chi Chuan practice accordingly. This is why the Tai Chi chuan Classics say that Yin and Yang interaction is ther criterion for determining one's skills. Today many people practice the Tai Chi Chuan Solo Form from either too hard or too soft.