According to the Concise Oxford Dictionary, dualism or duality is the theory recognizing two independent principles, and it provides examples of duality: mind and matter; good and evil in the universe. The brief definition of duality by the dictionary is clear enough, yet when it comes to the duality concept of yin and yang, Daoist students are quite often stumped.
We are often told by the great sages that metaphysics (the philosophy of mind) cannot be grasped using just the intellect; practice or cultivation is required to complement the understanding of their concepts. Yet Western Daoists tend to think that they first have to understand the duality concept of yin and yang fully before they can put it into practice. Believing in that, a number of them still struggle after spending decades studying Daoist texts trying to figure out this duality concept. And why yin changes to yang and yang into yin upon reaching their extreme states.
Duality in Daoist studies can be quite simple and easy if we do not overanalyze the concept or flogged it to ‘death’.
Perhaps, an easier way to comprehend the duality concept of yin yang is to refer to the basic underlying principles in the two primary hexagrams that of Qian / Heaven and Kun / Earth in the Zhouyi with reference to the Tao Te Ching. Since the holy sages have a deeper understanding of seen and/or unseen phenomena.
The oldest duality concept of nature is that of light and dark represented by unbroken and broken lines respectively that form a trigram and/or a hexagram in the Book of Changes. This ancient classic also differentiates between what is good and what is evil (another duality). The holy sages take the Junzi (superior man) and the Da Ren (great man) as examples of the good while the Xiao Ren (inferior man) represents the evil – which has nothing to do with religion; unless you want to hear what the Daoist heavenly immortals say about good and evil in the universe.
By the time of the Warring States in China, yang was inferred to represent light while yin represents dark. Because yang is light it can represent hot while yin being dark represent cold. Since the Great Treatise discussed light and dark spirits, later Daoists use metaphors to describe humans as ‘yang ren’ and ghosts as ‘yin kuei’ to differentiate between the living and the dead. By now the duality concept of yin yang has become so popular with the Chinese that they extend it to myriad things. Yet can we not see the duality of the dark and the light better than yin and yang?
The Heaven hexagram comprise of six unbroken or light lines while the Earth hexagram is made up of six broken or dark lines. Nature has it that Heaven provides light to brighten up dark Earth. Together, this means that Heaven represents pure yang (light) while Earth represents pure yin (dark), with humans (men and women – also a duality in later day usage) in between, just like Qi (breath or energy) that pervades the universe. In addition, ‘emptiness’ represents the imagery of Heaven (xu) and ‘stillness’ represents the image of Earth (jing). (See later.)
According to Daoist tradition, after the fall from Tao, by cultivating essence (meditation) and bodily life (virtues) humans can return to the Center (Zhong), the place where Heaven and Earth, and the ten thousand (myriad) things metaphorically resides.
With continual cultivation, humans can then progress from the Center to return to Heaven and Tao. Upon reaching Heaven and attaining Tao, man becomes an immortal with eternal life just like what Laozi indicated in his TTC chapter 16 using ‘empty’ and ‘still’. The metaphors, ‘empty’ (xu) and ‘still’ (jing) in chapter 16 infer to the practice of meditation. Read together with TTC chapter 42, the meditation involves breath (Qi) control. If we venture and read TTC chapter 14 on forms and formless, we may then understand what Laozi had seen during meditation. But if we ignore TTC chapter 18 on the cultivation of virtues after the fall from Tao, we could miss the return to Tao, like Zhuangzi of old even though this ancient sage had highly valued meditation in his writings.
In case students still do not understand the simple concept of duality in Daoist studies, cultivators use breath control meditation to merge or harmonize the duality of yin yang into one. No, this ‘one’ does not represent the Tao. More like the Center (Zhong). Unless you insist that the comment in the Great Treatise (Da Zhuang) that ‘One yin, one yang is Tao', is correct? Then perhaps you may have misunderstood the duality concept or that of the Supreme Ultimate (Taiji tu or Bagua).
However you can obtain a better understanding of the duality concept if you can stumble upon forms and the formless (or emptiness) during breath control meditation as indicated by the great ancient sages – Laozi and Buddha – in their teachings.
But how would you know, if you do not cultivate or practise meditation?