Why use the word "purple" as the emperor? Where is the earliest history?

1, ancient astronomers in China divided the main star in the sky into 28 stars with three walls, four images. Three yuan is Taiwei yuan, Ziwei yuan and Tianshi yuan. Among them, Ziweiyuan is in the middle, which is the place where the emperor in heaven lives, and it is called Purple Palace. The feudal emperor claimed to be the son of the Emperor of Heaven, so he also symbolized the palace where he lived as the Purple Palace in the sky.

2. Astrologers often use the trend of "Purple Star" to predict the good or ill luck of the emperor. Purple MSI is the brightest star in the sky, and the purple wall is surrounded by the surrounding stars. See point 1 for the reason.

3. The earliest time is not clear, but it should not be earlier than the Han Dynasty, because it was not until the period of Emperor Wu of Han Dynasty that Dong Zhongshu founded the theory of "harmony between man and nature" and "interaction between man and nature".

4. One more thing: ancient books are sealed with mud and covered with mud seals, while imperial books are made of purple mud, called purple mud books or purple characters, which are often decorated with dragons and phoenixes. I don't know if it matters. ^_^