The Simple Questions states in chapter 67: When the energy of an element has excess it will occupy the same position as the one that at that moment should be victorious, it will restrict it, and the insulted position will not be able to overcome it; when the energy of an element has deficiency and fails to overcome and occupy its own position by surpassing the insult and aggression ... it will be insulted.

The state of excess or deficiency of an element are the only causes of imbalance in the normal cycles and consequently are the two possible causes of disease.

Overacting or Cheng Cycle

It is that in which the natural action of inhibiting becomes excessive.

The rupture of the natural equilibrium leads one element to want to dominate another; this is known as overacting between elements.

The grandfather (possible excess) overacts on the grandson (possible deficiency). It is also called a relationship of aggression.

• Wood can overact on Earth by growing its roots too much and taking up Earth's space.
• Fire if in excess melts Metal until it is exhausted.
• Earth can be so impermeable that it does not allow Water to seep through or it seeps too much.
• Metal in excess would not allow any tree (Wood) to grow by cutting them all down.
• Finally, Water can extinguish Fire when there is too much of it.

Wood overacts on its grandson Earth; Fire overacts on Metal; Earth overacts on Water; Metal overacts on Wood and Water overacts on Fire.

Counteracting or Wu Cycle

Contrary to the overacting cycle, in the counteracting or contradominance cycle, the element turns against its inhibitor. The grandson attacks his grandfather. It is also called insulting.

The condition of counteracting of one element over another responds to the combination of excess of the counteracting element and the deficiency of the element being countered.

• Wood very hard (in excess) weakens Metal leaving it without edge to cut.
• Fire in excess evaporates Water.
• Earth can be so hard or without nutrients that it ends up not allowing Wood to grow.
• Metal can be so abundant that Fire is extinguished before it can melt it.
• Water can be so abundant that Earth never manages to drain it and it rots.

Generally it takes many years of bodily neglect, very strong external pathogenic factors or a combination of both to reach counteracting. In the clinic we know them as chronic degenerative diseases, although not all chronic degenerative diseases belong to this relationship between elements.

These cycles set forth above together with the cycles of generation and control constitute the bases of pathophysiological reasoning, as well as those of diagnosis and therapeutic application.

See more in Theory of the Five Elements