Medicines that primarily function to pacify the liver and subdue yang, and to calm wind and stop convulsions, are known as liver-pacifying and wind-calming medicines. Although there are many causes for the internal stirring of liver wind and the ascendant hyperactivity of liver yang, they generally fall into two categories: deficiency and excess. Deficiency is often due to "water failing to nourish wood," while excess is usually caused by "extreme heat producing wind." Therefore, these medicines are mostly cold or cool in nature and should be used cautiously to avoid excessive attack in cases of deficiency-cold of the spleen and stomach or yin deficiency and blood deficiency.