Here's an interesting article on the Buqi system and founder of this system, Dr Shen Hongxun, written by Dr Marc Price including an explanation on the understanding of Qi and the theory of the double vicious circle of illness.
For the full article : https://www.taichiunion.com/articles/the-buqi-system/
Marc is a 'Senior Instructor' member of the Tai Chi Union of Great Britain and holds classes on Taiji and meditation in Worcester and online at: