To survive, ancient people dwelling in the mountains and wilderness constantly struggled against the harsh natural environment. Through prolonged foraging, they repeatedly experimented and observed, gradually accumulating knowledge of plants and animals. For instance, certain wild fruits and roots were discovered to relieve bodily discomfort, whereas some seemingly palatable plants could induce dizziness, or even death.

The discovery and application of fire brought revolutionary changes to tribal life, including the consumption of cooked food, which shortened the digestive process; the warmth of fire, which dispelled cold and dampness from caves; and bright firelight, which extended the hours of activity. As living conditions improved, the incidence of illness among early humans correspondingly declined.

When using heated stones for warmth, early humans discovered that applying hot stones to specific body parts could relieve pain, which was the prototype of moxibustion therapy in later generations. During hunting, injured individuals used sharp stone fragments to puncture abscesses and drain pus, finding that this method facilitated recovery. These direct observations, born from the demands of survival, laid the foundations of medicine.

Early humans deepened their reflections on natural phenomena. Zhouli (Rites of Zhou) written in the Zhou Dynasty records: “Epidemic diseases occur in all four seasons: in spring, headache-related disorders; in summer, pruritic and scabious disorders; in autumn, malarial disorders with chills; and in winter, cough and dyspnoea  disorders.” This description of “seasonal diseases” indicates that ancient people had already recognised the link between disease and seasonal change.

Ancient people’s knowledge of medicinal substances also emerged from direct observation of nature. Shijing (Classic of Poetry), dating from the early Western Zhou Dynasty to the mid-Spring and Autumn Period, records over fifty plant species with medicinal value. For example, “Fuyi (Plantains Herb, Herba Plantaginis)” mentioned in Zhou Nan (Odes of Zhou and the South) section of the Shijing (Classic of Poetry), refers to Cheqian Cao, a plant whose leaves and seeds are used as medicinal and have a diuretic effect.

During the Spring and Autumn Period, Laozi also mentioned the cosmogony in the Dao De Jing (Tao Te Ching): “The Dao begets One; One begets Two; Two begets Three; Three begets all things.” He described the Dao as unique and that the Dao itself contains the two qi of yin and yang. Yin and yang interact to form a balanced state, from which all things arise. This philosophical concept, when introduced to medicine, posits that health depends on the dynamic balance of yin and yang. When this balance is disrupted, disease arises. Thus, the fundamental principle of traditional Chinese medicine (TCM) is to “harmonise yin and yang”.

Early humans possessed both an intuitive understanding of nature and profound philosophical reflection, laying the foundation for the unique path of TCM’s development. Unlike purely empirical medicine and distinct from abstract speculative philosophy, TCM emerged from the interaction between observation of nature and metaphysical thinking, forming a medical system that combines practice and theory.