There are several important concepts in Feng Shui, one of which is the so-called "Yin-Yang Theory". The theory of yin and yang emphasizes that everything in the world has yin and yang. For example, female, moon, right, inner and even numbers all belong to "Yin". Male, grandson, left, face and odd number belong to "Yang". The secret of good geomantic omen lies in skillfully achieving harmony between yin and yang.
The basic content of Yin-Yang theory includes four aspects: opposition of Yin and Yang, complementarity of Yin and Yang, growth and decline of Yin and Yang, and transformation of Yin and Yang. In geomantic omen, yin and yang are used to express the form of qi. Yin and Yang forces jointly create movement and balance it in the world. Yin Qi's flow is relatively slow and dispersed, and the temperature is low, while Yang Qi's is the opposite.
Feng Shui is developed on the basis of "Yin and Yang" and "Five Elements". In ancient times, all the existence of nature was established as "wood, fire, earth, gold, water-five elements" and its opposite "yin and yang" nature. Geomantic omen is the combination of "five elements" and "yin and yang", which classifies things into disciplines with certain attributes. For example, "Yin" tastes dark, cold and shabby, while "Yang" means bright, warm and brand-new. There is also a mutual growth and restriction in the five elements. In geomantic omen, no matter according to yin and yang or five elements, we can judge the state of the environment, supplement the insufficient qi, restrain the excessive qi, adjust the balance and create a happy life.