Lao Zi mentions that “Difficult and easy compliment each other, Long and short contrast each other, High and low rest upon each other, Front and back follow each other , Opening and closing mirror each other”. Lao Zi Daodejing.
As Lao Zi says above when we perform our Lishi taijiquan form the individual should become more aware of the transformation of their taijiquan form practice, by concentrating on the changing of Yin to Yang and vice-versa as they perform each of the movements that make up their Lishi taijiquan form. The study and practice of any style of taijiquan form work has many levels to them that each individual must progress through if they truly want their taijiquan practice to achieve a high standard of skill. Unfortunately there are many individuals who are lazy in their practice and think that simply practicing the Lishi taijiquan form moving from one posture to another in a slow and relaxed manner is high quality Lishi taijiquan practice. Actually this is the lowest level of taijiquan practice as the individual does not wish to apply the changing of Yin and Yang which will gradually encourage them to connect and involve their mind, body and spirit together into their practice.
There are many examples of the principles of Yin & Yang being used in the practice of the Lishi taijiquan form work. One example that each individual should be able to distinguish Yin & Yang from is between substantial meaning fullness (Shi) and insubstantial meaning emptiness (Xu) as their bodyweight transfers from one leg to the other as they perform their stepping actions. Another example is to become aware of the closing and opening of their joints in a balanced, smooth and even manner as they progress from one movement into the other. The closing action of the joints should be performed with a softening, contracting feeling, whereas, the opening actions should be performed with a gentle feeling of expanding to release. As the individual becomes more aware of employing more principles of the changing actions of Yin to Yang and vice-versa then their Lishi taijiquan skill will definitely grow in their ability to manipulate the circulation of Qi throughout their entire body to strengthen and maintain their health and promote long life (Chang Ming)
The growth of each individuals ability to fully connect to their body, mind & spirit can only be achieved through taijiquan practice by developing their skill to manipulate and harmonise the ever changing principles of Yin & Yang and vice-versa. This can only happen through regular daily practice as Lao Zi mentions the “Difficult and Easy compliment each other” sadly to many individuals take the easy option of practicing the Lishi taijiquan form by simply practicing and concentrating on the correct order of the each Taiji posture leading into another rather than concentrating on the quality of each movement through the interpretation of Yin & Yang.