According to Chinese tradition, the living, and here especially the man is an organization resulting from the combination of matter – the physical body or physical – such as yin and energy – that drives the field – yang. The balance between these two components determines the state of health.
The disruption of this balance is responsible for the disease. Any disturbance such as to upset this balance primarily affects preferentially energy. For 
example, an excess of yang can cause sudden pain, inflammation, spasms, headache or an increase of tension. An excess of yin can lead to widespread pain, feeling cold, fluid retention or fatigue.
The energy (Qi) is movement and disturbance which is the obstacle to the movement: the blockage. The blocked energy in a region of the body material accumulates upstream of the blockage, while areas downstream of the blockage will be in energy deficit.
In the presence of a state of pathology the acupuncturist describes what will establish the diagnosis by looking for levels at which energy is blocked, and what the reason is for the blockage. It will then apply this treatment by removing the blockage and correcting, if possible, the reason for the blockage. The needle, among other means, will enable him to direct the course of energy.
The energy flows along particular conduits called meridians, and, from these meridians, spreads throughout the body to breathe vitalizing principle (yang) to all constituents of the body. It has some correlation with the blood, which itself flows through conduits (vessels) and spreads throughout the body to irrigate principle yin.
In addition, there are several energies, each with its own specialty, in addition to the main meridians. There are still a host of functions to different meridians. The balance of the human body must always be evaluated relative to that of its environment, and cycles of ranging changes in rhythm, cycles with which it must remain in harmony with for the physical connections (five elements) that serves as benchmarks for the acupuncturist to establish its diagnosis and treatment, according to rules that are subtle of their origins in Taoism.
