At the basis of all is Qi. Because of its fluid nature, Qi is very difficult to define; it assumes different manifestations and can be different things in different situations. The concept of Qi is not exclusively Chinese; Hindus refer to it as “Prana”, the Greek “pneuma” and the Hebrew “ruakh” all have much in common with it. It has been translated as “energy”, “material force”, “matter”, “ether”, “matter-energy”, ”Vitality”, “vital power”, “vital force”, “life force” or “moving power”. Qi is the basis of all the infinite manifestations of life in the universe, including minerals, vegetables, man and animals. Ancient Chinese philosophers believed that life and death themselves are nothing but an aggregation and dispersal of Qi.
“Qi produces the human body just as water becomes ice. As water freezes into ice, so Qi coagulates to form the human body. When ice melts, it becomes water. When a person dies, he or she becomes spirit [shen] again. It is called spirit, just as melted ice changes its name to water”.
Wang Chong (AD 27-97)
The workings of the body and mind are the result of the interactions of Vital Substances all of which are manifestations of Qi in varying degrees of materiality, ranging from the completely material, such as Body Fluids, to the totally immaterial, such as the Mind or Spirit (Shen).