The burial objects found in archeological excavation sites mentioned in the preface of this book indicate the vague notions people had about the “soul” and the “next life”. Primitive worship and totems, an animal or other natural object that was chosen and respected as a special symbol of a community or family, arose. Unpredictable dreams and incomprehensible thunder and storms were considered to be a “deity”, the most powerful force in nature. Based on their repeated experience and lessons from their survival activities, people attempted to find out and follow “the law” or regular patterns of nature.

In primitive societies our ancestors developed the notion that humans and the outside world exist in an antagonistic relationship. After many changes of social formation, “philosophy” took shape in the social and cultural soil of ancient society.

The worship of nature and ancestors in primitive society was gradually replaced by worship of “Emperor of Heaven”. But as people gained a deeper understanding of society and nature, these beliefs diminished and in the Zhou Dynasty （11 ^th century-221 B.C.）, the conception of “respecting the heaven and protecting the people” emerged.

When he commented on the social thoughts of the Xia, Shang and Zhou dynasties （21 ^st century B.C.-221 B.C.）, Confucius said, “people of the Xia Dynasty honored fate”, “people of the Shang Dynasty honored god” and “people of the Zhou Dynasty honored law and discipline” ^[16].

In the Spring-Autumn and Warring States Periods （770-221 B.C.） the sprout of dialectics and dialectical thinking began to take shape. These included the concepts of yin and yang, the Bagua （Eight Trigrams） and qi.

”Qi”, which we discussed previously, is an important idea in all of Chinese philosophy, because it is the starting and ending point for the ontology and epistemology of the universe. It permeates all knowledge of one’s own world and the outside world.

Originally, qi referred to the air in the sky, the breath of humans, or the atmosphere of the earth. Gradually, ancient people began to conceive of it as the foundation for the growth of all things on earth. Wind was considered to be the qi of nature in the Shang Dynasty （16 ^th century-11 ^th century B.C.）, and qi was used to explain earthquakes in the Zhou Dynasty （11 ^th century-221 B.C.）. Later it was thought that all tangible things on earth were the result of transformations of invisible qi. Ancient Chinese thought qi was the most basic substance that sustained life. Where there is qi, there is life. Life essence came from the heavenly qi while the form of the human body came from the earthly qi.

“Everything on earth is formed by something, and something is generated by nothing.” ^[17] （ Lao Zi） This laid the foundation of the fuzziness of qi.

The book Guan Zi says, “one survives when he is full of qi, and one dies when he loses all qi.”

The statement above emphasizes that qi is the foundation of life, and if there is no qi there is no life.

Since essence comes from qi, when it combines with qi, everything on earth is generated from it. （ Guan Zi）

Ancient Chinese considered “spirit” to be similar to “qi” and “essence”. It was a special kind of qi or an aspect of qi, and it was an internal, dynamic material force in the development and changes of things.

The original meaning of yin-yang was the sides facing or opposing the sun. That is to say the side facing the sun pertains to yang, while the side opposite to the sun is yin. Later, the meaning was extended. Yang was associated with such qualities as brightness and warmth while yin was associated with such qualities as darkness and cold. Because the sun is in the sky, it is yang and the earth is yin; the upper part of an object is yang and the lower part of it is yin; motion is yang and motionlessness is yin; qi is yang and form is yin. Generally speaking, all things and phenomena in nature can be categorized into yin and yang. The qi that constitutes the whole universe is also categorized into yin （heavy and turbid part） and yang （light and pure part）.

People began to think that any change in natural phenomenon was the result of the waxing and waning of yin and yang, which means the concept of yin-yang transformed from denoting a specifc thing into an abstract concept. It is the universal law of development and change. When yin and yang reach the extremes, yin can transform into yang and yang into yin.

The Book of Changes （ Zhōu Yì, 周易） says, “transformation is caused by interaction between two things. This is the constant pattern of life.” The qualities and transformations of yin and yang comprise the constant patterns of all things. What should be emphasized is that the transformations are not from the confict between yin and yang, but their harmony, which moves in constantly repeating paterns.

In the Spring and Autumn Period （770-476 B.C.） authority and legitimation were changing, and people were not satisfied with the old concept that everything was created by god. Atheism prevailed, allowing new ideas about yin and yang, and five phases came into being. The five phases had their own special functions, and through understanding these and their corresponding resonance with things in the same category, people understood the basic processes of life and events through analogy. At this time, the doctrine of generating and restraining sequences of the five phases gradually developed, and this became the basis for recognizing all things in the world.

As the general level of knowledge improved, people had profound insight into their interrelationships. The theory of the five phases was used in agriculture and metallurgy. Later, it became a metaphysical philosophical concept and was applied to various fields, and was accepted by different schools to illustrate the complicated relationships among multiple objects.

The generating and restraining sequences among the five phases dominate all things on earth, including human social behavior and mental activity. They are used to explain the five attributes of the five zang-organs and the five stages of life, namely birth, growth, prime, old age and death, as well as the laws of generating, restraining, over-whelming and counter-restricting. The five phases serve as a complement to the theory of yin and yang, and are one of the important components of the basic theory of traditional Chinese medicine.

The doctrine of the five phases has become a mode of thinking by which everything can be induced and interconnection and change between things can be deduced.

The doctrine of the Bagua （Eight Trigrams） is also an essential part of ancient philosophy. Each “hexagram” consists of three lines, each line is either broken or unbroken, and represents yin （——） and yang （—）, respectively. The eight hexagrams are as follows: Qian （Heaven）, Dui （Lake/Marsh）, Kun （Earth）, Zhen （Thunder）, Xun （Wind）, Kan （Water）, Gen （Mountain）, and Li （Fire）. According to legend they were invented by Fu Xi and developed by King Wen of the Zhou Dynasty （11 ^th century-256 B.C.） and recorded in The Book of Changes.

The eight images are not eight equal material elements but are rather symbols based on the fundamental nature of Qian-gua and Kun-gua.

The basic symbols of the image—numerological system of Bagua are “—”（yang）and “——”（yin）, and the basic logic and significance of the hexagrams derives from a profound understanding of yin and yang. The Book of Changes consists of sixtyfour hexagrams, from which the intricate relations among all things on earth can be deduced, including rejecting and attracting, opposing and complementing each other, cause and result, restraining and generating, and interaction and deviation. From this we can see the birth of a primitive sort of dialectics, and it is this which has given the theory of yin and yang the remarkable ability to change and adapt to the times without losing its relevancy.

The theories of qi, yin and yang, the five phases and Bagua constitute the core of the natural philosophy of traditional Chinese medicine.

In ancient times, because the levels of both the material production and knowledge production were low, people could not understand some natural phenomena and some aspects of human physiology. They stood in awe of nature. As a result, nature worship, worship of reproductive organs, totemism, ancestor worship, and ghost and god worship were prevalent. These were the earliest religious activities and were based on their concepts of the spirit world. Eventually, ghost, god, and ancestor worship made up the primitive worship system, which had grown out of people’s consciousness and customs.

Destiny, ghosts and gods always played important roles in social ideology in the period of the slavery system. In the Shang Dynasty （16 ^th century-11 ^th century B.C.）the slave owners and nobility strongly believed in ghosts and gods. They advocated a theology based on the will of destiny. In the imperial court there were priestofficials, or theocrats, who took part in state politics in the name of gods. At that time, the “Emperor of Heaven” was the sovereign god, dominating the whole world. Destiny was irresistible and, along with ghosts and gods, the world was controlled by them.

After the social instability and transition from the Shang Dynasty to the Zhou Dynasty （16 ^th century-221 B.C.）, the status of human beings gradually increased. But destiny, ghosts and gods were still the weapons of aristocracy used to consolidate their rule over the people.