Hair during the various stages of one's life exemplifies the physiological changes which are connected to the developments of kidney qi or the vital energy of the body. 头发是生命中各阶段里的生理变化的主要指标，由于肾气兴旺才得以长得既长又多，乌黑光亮。
The occurrence of a disease is related to both pathogenic factors and vital qi. 疾病的发生和邪气及正气都相关。
