The concept of "essence and spirit" in traditional Chinese medicine belongs to the philosophical category, of course, it has its material basis, and it cannot be specific to specific substances, but is an abstract summary of specific substances.

Essence refers to the subtle substances that constitute the human body and maintain human life activities, and it is also the material basis for human growth and development and physiological functions of various organs. You can understand it as a specific organ, a specific tissue, a cell, or even a specific biochemical substance at the molecular level. Of course, cell biochemical substances can be detected by instruments, but due to the limitation of traditional thinking and theoretical research level of traditional Chinese medicine, we are still unclear.

The role of these specific substances in traditional Chinese medicine.

Qi is the most basic substance that constitutes the human body and maintains human life activities. It is not only the concrete substance on which the human body depends for survival, but also the general term for the functional activities of human viscera. If essence is a pure substance, then qi is the function of substance.

God: essence produces qi, which is transformed into god, and god is the master of life activities. It means that only matter can produce function (there is no function without matter), and the synthesis of matter and its function is God. God is a state of mankind. The existence of God means that matter and its function are normal, while the absence of God means that matter and its function are abnormal.

Personal understanding, a bit abstract.