For many years it was believed that Qi was unmeasurable but the Covenite scholar Mozi had the insight to appreciate that whilst Qi itself is intangible its effects were not and hence developed the Qi Scale which (by analysis of certain socio-economic phenomena) allows an assessment to be made of the level of Qi prevalent in the Demi-Monde.
He went on to postulate the First Law of Qi which states:
Qi can neither be created or destroyed, it can only change form from Yang to Yin (or vice versa). In a closed system (such as the postConfinement Demi-Monde) the level of Qi will oscillate around an unchanging mean, also known as the Base Level
As can be seen the Ages of Yin and Yang alternate. This is the Cycle Theory of History (or as it is known in the Coven, HerTory) which underpins the Concept of Qi Equilibrium.
The thinker Too Zi rejected the Concept of Qi Equilibrium and by making amendments to the Qi Scale showed that the levels of Qi in the Demi-Monde had been rising inexorably for four thousand years. This allowed him to postulate a Second and Third law of Qi.
When two systems (the Demi-Monde and the Spirit-World) each in its own equilibrium with respect of Qi, are put in connection with each other there will be an exchange of Qi unless and until they come to be jointly in Qidian equilibrium.
Qi will flow from a higher level Qi system to a lower level Qi system.
THE 2ND GRAPH WON'T POST - I'LL GET TO IT LATER!