What does "Purple Qi coming from the east" in Feng Shui from the Book of Changes mean?

"Purple Qi comes from the east", one of the Taoist anecdotes. The classic book is "Guan Ling Yin Nei Biography". Later, many Taoist biographies also contained similar descriptions. It is said that Laozi, the founder of Taoism (honored as Taishang Laojun in Taoism), faced with the decline of Taoism in the world, prepared to leave the Zhou Dynasty and live in seclusion. "The Legend of Youlong" says: I want to go to the Liusha Kingdom in the west in order to educate foreign peoples. As a result, a line of purple gas moved from east to west until it reached Hangu Pass. Yin Xi, the doctor of King Zhao of Zhou Dynasty, was good at observing the omens of the movement of stars in the sky. He knew that a saint was going to pass through Hangu Pass, so he resigned from his position as a court official and went to Hangu Pass to serve as a pass order. He held a fasting ceremony, burned incense on both sides of the road, cleaned everything along the way, and waited for the arrival of the saint. Soon, I rode a green ox and slowly entered Hangu Pass. Guan Ling Yinxi worshiped Laozi as his teacher and asked Laozi to write the Tao Te Ching, which has been passed down through the ages.

In Chinese folk, purple air coming from the east has become a symbol of auspiciousness, and many literary works have plot interpretations based on it. For example, Chapter 77 of "The Romance of the Gods", "Laozi transforms one Qi into three Qings" is an example. This work is based on many Taoist documents and makes an artistic use of the story of the coming of purple energy from the east. It is quite interesting to read. In the past, during the Chinese New Year, people always liked to post Spring Festival couplets saying "Purple Air Comes from the East", which shows that the story of Lao Tzu passing through Hangu Pass has been spread for a long time.