The concept of the Eight Principles or Ba Gang in Chinese medicine theory is the foundation for all other methods of pattern formulation. It is the basic framework of pattern identification allowing practitioners to identify the location and nature of disease, as well as structuring a treatment protocol.
The Eight Principles are:
Differentiation of patterns by the Eight Principles forms the theoretical basis for all methods of pattern identification, whether it be patterns according to the channels or the Zang–Fu organs, and it can be applied to all pattern identification methods. They are applicable in every case. It is important to realise that using the Eight Principles does not mean that a disease or disharmony can be rigidly catergorised to fit clinical manifestations. However, it does allow practitioners to unravel complicated patterns to identify the most relevant and essential clinical manifestations.
Neither should they be used as an “either-or” approach. It is not uncommon to see a condition that is simultaneously interior and exterior for example. There will be cases which may not involve all of the characteristics listed above. One such example is that of blood deficiency, which does not involve Hot or Cold.
Interior-Exterior: Differentiation on the basis of the location of the disharmony, NOT the cause.
- Exterior: For conditions affecting the skin, muscles and channels as they are on the exterior of the body. Clinical manifestations arise out of exterior invason by pathogenic facts and are divided into two types.
- Interior: A disharmony or imbalance which is defined as one which affects the Zang-Fu Organs. This may or may not have originated from an exterior pathogenic factor. Generalising the clinical manifestations of interior conditions is not possible as they will relate to the organ(s) affected and to other aspects of the Eight Principles, i.e. Hot-Cold, Full-Empty, Yin-Yang.
Hot-Cold: Describes the nature of the pattern and its clinical manifestations depending on if they are combined with a Full or Empty condition.
- Hot: Classified as Full-Heat or Empty-Heat. Full-Heat arises from an excess of Yang, while Empty-Heat originates from a deficiency of Yin.
- Cold: Classified as Full-Cold or Empty-Cold. Full-Cold arises from an excess of Yin, while Empty-Cold originates from a deficiency of Yang.
Full-Empty: Differentiation between Full and Empty is very important and is made according to the presence or absence of a pathogenic factor, and the strength of the body’s energies.
- Full: Characterised by the presence of a pathogenic factor which may be interior or exterior and by the fact that the body’s Qi is generally intact.
- Empty: A condition characterised by weakness of the body’s Qi and the absence of a pathogenic factor. Empty conditions can relate to Qi, Blood, Body Fluids, Yin and Yang.
Yin-Yang: In terms of the Eight Principles, Yin-Yang can be considered in the general sense, or as a summarisation of the other six principles. Specifically, Yin-Yang can define the two types of emptiness as described above, or two types of collapse. These are the collapse of Yin and the collapse of Yang. They are an extreme form of emptiness, which implies a complete separation of Yin and Yang, which is in many cases, but not always, followed by death.