The Fundamental Substances: EssenceTraditional Chinese medicine (TCM) is built on a foundation of more than 2,500 years of Chinese medical practice. TCM is a holistic practice that treats the system as a whole, rather than alleviates specific symptoms of illness.
Within the TCM, there is a substance called "essence."
According to TCM, "essence, qi, blood, and body fluid" are the four basic substances that make up the human body and maintain the latter's vitality. The viscera, meridians, internal organs, and other tissues of the human body are composed of these four basic components and rely on the nourishment of essence, qi, blood, and body fluid to conduct normal physiological activities....
Source: The Fundamental Substances: Essence (https://www.theepochtimes.com/health/the-importance-of-essence-qi-blood-and-body-fluid_4931187.html)