II. Farewell to the old and blessing's knocking at the door

"Door" here refers to the auspicious door of Taiji.

As we all know, the door is the access to a building. There is a door in house, and there are also all kinds of doors in a city, temple and mountain.

In the exercise of Double Fish Hung on the Wall（Shuang Yu Xuan Ge）, left foot step forward from empty step to bow step. Meanwhile, swing hands with the flow in the round way, and folded crosswise in front of chest, forming the "left door". Then, the right foot step forward from empty step to bow step. Meanwhile, swing hands with the flow in the round way, and folded crosswise in front of chest, forming the "right door", thus making up the Chinese Traditional character "door" (see Figure 2).

As we all know, the doors all include rich Chinese traditional culture in the minds of the Chinese people, which embody the principles of yin and yang between heaven and earth, as well as the world or universe, and presents Yi-ology philosophy.

Now I will take the doors of Beijing city as an example. "Ba Gua Tan Mi" written by renowned experts Mr. Zhang Ruiwen has concluded, "Beijing outer city has seven gates, namely Yongding Gate, Zuo'anmen, You'anmen, Guangqu Gate, Guang'anmen, Dongbianmen and Xibianmen. Seven is the number of Shaoyang. The inner city has nine gates, namely the South Three Gates including Zhengyang Gate (commonly known as the front door), Left Chongwenmen and Right Xuanwumen, the North Two Gates including East Andingmen and West Deshengmen, the East Two Gates including South Chaoyangmen and North Dongzhimen, as well as the West Two Gates including South Fuchengmen and North Xizhimen. Nine is the number of Laoyang."

Why the number nine and seven are adopted in the inner city and outer city? Mr. Zhang Ruiwen continued to explain, "It is because that the gate is the only way of daily life. In the social life, the emperor has occupied the imperial throne, so he hosts the inner city with nine, and governs the outer city with seven. As for the gate configuration of inner city, the south side is odd and yang, and the north side is even and yin.

In addition, the height of Zhengyang Gate, namely the main gate of inner city, is nine chi nine cun, reflecting the number of Laoyang.

These conditions have explained that the configuration and design of the doors of Beijing city are based on the idea of Yin-yang and eight diagrams of the Book of Changes.

It can be seen that the simple traditional character "door" is not only a Chinese text symbol, but also a holographic logo loaded with ancient scientific knowledge and cultural attitudes.

(By Zhang Guangde)