Oneness, duality and back to oneness
A whole day made of 24 hours is characterised by hours of light and hours of darkness that slide into each other in a smooth and imperceptible manner. This indicates that light and darkness mingle with each in transient 'oneness' forever.
In a day, the time span from midnight (Nadir) to midday (Zenith) is characterised by the sun rising and climbing into the sky to reach the Zenith, whereas the time span between midday (Zenith) and midnight (Nadir) is characterised by the sun setting and hiding more and more from view, into darkness, reaching the Nadir.Yet, this observable duality is nothing else but the 'side effect' of the incessant cycle from sunrise - sunset, winter-summer and around again with focus on the sun.
Ancient texts (i.e."Huangdi Neijing-Sowen" 皇帝內經 -素聞 ) expresses the phenomenon described above as follows:
"When Yang (Sun, light) rises, Yin expands (away from the contraction which is natural to it), when Yang (Sun Light) declines, Yin hides (contracts to its maximum)*."
Thus, when the sun rises, light and warmth come and i.e. the flowers open. When the sun dawns, light 'succumbs to darkness and coldness.' Darkness is absence of sunlight. This is when the moon appears.
The sun in Chinese is called "Taiyang 太陽, greatest yang" and the moon "Taiyin 太陰, greatest Yin".
Yang and Yin are nothing else but metonyms of sun's and moon's expressions and behaviour.
In terms of human physiology, the early part of the day gradually leads to activity, whereby people get out of sleep and go about their own affairs 'using energy' and 'connecting' with the world, perceived as 'external' to them. The later part of the day, on the other hand, gradually leads to retreating: people go back to their homes, seek rest and 'connect' with themselves, with their perceived 'inner' world. This is the time to replenish and refuel one's power.
Both moments, despite appearing 'opposite' are one movement, one life, one cycle: one needs 'to use' in order to live and 'rest' in order to refuel. The latter aspect of life, is associated with transformation 'hua 化': whatever has been gathered in the daily connection with the 'external' world (food, experiences, air, sound, emotions, odours, stimulation etc) undergoes a metamorphosis and becomes 'like me'.
From the point of view of both Chinese philosophers and doctors, the propriety, correctness, wisdom, truthfulness and uprightness of this process rests on the 'logos' beyond all observable phenomena, Dao, the 'void', the path from which everything proceeds. As common denominator of all life it underpins the 'oneness' of all living beings, beyond the limited perception given by the 'external' world' of multiple phenomena, where it would seem that all life is founded only upon duality and difference. Transcending the predicament of the world of form, requires moving beyond the perception of duality and change in order to focus on the understanding that not only the fundamental structure of each existence, but also the ultimate abode of each life journey is nothing else but Dao 'oneness'. All forms move from within this 'oneness', this 'centre, zhong, 中'. Regardless of how the whole world seems broken into discreet and separate forms, the sage never departs from focusing on and positioning him/herself in 'oneness'. Thus, he/she moves in the world, without allowing anything to separate him/her from 'Dao' and from resonating with the whole.
To understand the unity of Qi, through understanding the seasonal and day-night cycles and how in human life resonates with it allows all of us to reach a new and deeper level of 'reading' and making sense of our lives. Health is thus not a state of the body, but a state of being, of mindset. Moving in 'use' and in 'refuelling' occurs during the whole of one's lifespan: all life is nothing else, but an exercise of emerging from the 'void' as co-creators of Dao and going back to it in a 'pause' that allows, through a renewed connection with it all, that creation happens over and over again.
All nature reflects this rhythm.
Why is this relevant to Chinese medicine?
The 1st Chapter of the "Huangdi Neijing - Suwen 黃帝內經 - 素聞“, stresses how, in order to be healthy we need to make the shift not from worldly to heavenly concerns, but from making a too sharp distinction between "inner" or "outer' directions, staying centred in Dao, which is where all duality collapses.
* 1. For more on this please read: Huangdi Neijing - Sowen Ch 1
* 2. In the evening the sun drops out of sight and it may seem that darkness swallows it.