Recently I received quite a few questions about, in my opinion, what is Cha Qi? To try to answer this, we have to ask first – What is Qi? I did some research, plus a bit of my own experience/understanding, on this topic. Starting from the very initial definition of Qi as appeared in Huangdi Neijing (Yellow Emperor’s Inner Classic) – the earliest theoretical and medical work for traditional Chinese medicine, let’s explore this fantastic old wisdom which is so fundamental to Chinese philosophy and medicine, and is still shining in the 21st century!
I bet we all heard many different explanations, experience and definitions as what is Qi. “Life force”, “energy”, “heat”, “pulsation”, “sweat”, “wind”, etc. But it would be essential to know the origin of the concept of Qi. And I found it in the ninth treatise of Neijing:
In this treatise, Huang Di (Yellow Emperor) asked QiPo, “So, tell me, my dear Teacher, what is Qi?”
And Qipo answered cannily, “This is the secret of ancient Saint, and the secret passed to me by my teacher!”
Huang Di pushed on asking, again, “Please tell me the secret, please!”
“All right, all right…”, said Qipo, “Listen. 5-day is one “Ho”, 3 Ho is one Qi, six Qi is one Shi (season), and four Shi is one year. …”
Strange, isn’t, that “the secret” is that Qi is a unit of every 15-day in a year. More precisely, according to Chinese lunar calendar, a year is divided into 24 jie-qi (Solar Term). Every 15° on the orbit (the Ecliptic) is one jie-qi. So 24 jie-qi gives a complete circle of 360°.
Simple, right, a Qi is one 15° of the orbit on which the Earth rotating around the Sun. Why Qipo is so enigmatic about this? We have to understand, in that time, thousands years ago, knowing the rhythm of the Earth’s change in a year would meant you were in control of the information needed for agriculture – and that was almost everything your people would care!
Every change from one jie-qi to the next one means the Earth is experiencing a change in some natural phenomenon, whether it be the weather starts to get warmer, the grains start to be plump, or the winter is at its extreme. Qi is the rhythm of the change of the Earth.
I’ve read people relate the concept of Qi to the concept of Nepheshor Ruach as appeared in the Hebrew Old Testament. All the three concepts have multiple meanings in their own culture, and indeed some are similar such as all are related to the life force. However, none of the two old Hebrew wisdom are related to the rhythm of the Earth’s change.
One most common term people relating to Qi is “energy”. How to go from the original concept as a rhythm to “energy”? When we talk about rhythm – or frequency, we are actually defining a phenomena of wave. And wave is “a disturbance that propagates through space or spacetime, transferring energy and momentum and sometimes angular momentum”. Furthermore, according to modern physics, all objects exhibits properties of wave and particles (wave-particle duality).
So while Qi reveals to us, physically, either as “heat”, “pulsation”, “wind(breath)”, the behind-the-scene work – or say metaphysically – of Qi is to regulate the rhythm of the change of the Earth. And old Chinese wisdom believes that holistically the Earth, the people, and in fact everything in the Nature, are one in essence. So the Qi that regulates the change of the Earth also communicates with the Qi that regulates our body’s work, and the plant’s growth.
Hope I am contributing a little bit on this tremendously huge topic. There are still many things for me to learn and to ask, so your opinions are very welcomed here 
Guang
