Six Exogenous Factors
Spring-wind, summer-heat, summer-fire, later summer-dampness,
autumn-dryness, and winter-cold are the six variations in the
climate of the four seasons. They are also known as the "six
climatic factors" or the "six exogenous qi."
The human body has the ability to adapt to climatic variations.
However, when bodily resistance is too low to adapt to climatic
changes or if there is an abnormal altering of the weather which
surpasses the body's adaptability, then the six climatic qi will
become pathogenic factors bringing about the occurrence of disease.
Therefore the climatic qi are all considered to be exogenous
Diseases which are not caused by exogenous pathogenic factors,
but have symptoms similar to the syndromes of wind, cold, summer-heat,
dampness, and dryness are termed internal heat, internal damp, internal
dryness, and internal fire. These endogenous pathogenic factors are
the outcome of dysfunctions of the zang and fu organs.
More about the Six Exogenous Factors:
Fire Heat and Mild Heat.