The relationship between yin and yang has two kinds. When yin is strong, yang is weak, or when yang is strrong, and yin is weak. These are the imbalances between the two onditions. And as conditions change constantly, it will come to the opposite side of the imbalance, which is called alternative predominance between yin and yang.
Our ancestors explained some climate change and body change with the help of this theory. If one year is usually rain and make the weather so wet, then next year will turn to be dry instead. So does the body change. If a person suffer a terrible diarrhea and his hands and feet are totally cold, which means pathogenic factors is strong. It belongs to asthenia cold syndrome. Then healthy energy is strong than pathogenic factors, these syndromes will disappear. And after that pathogenic factors will be strong, these will occur again. This condition of circulation is called alternativec predominace between yin and yang.
