The introduction of fire and water is not good.

The heart belongs to fire, and the kidney belongs to water. Fire and water restrict and interact with each other to maintain the dynamic balance of physiology, which is called "combining fire and water". Insufficient kidney water can't help heart fire; Or because of heart fire and kidney yin injury, this loss of coordination leads to upset, insomnia, nocturnal emission and other diseases, which means that fire and water are incompatible. See the article "Heart-kidney disjunction".