Why is the tortoise called Xuanwu?

Xuanwu originally meant Xuanming, and the ancient sounds of Wu and Ming are interlinked. Xuan means black; Ghost means yin. At first, Xuan Ming described the tortoise divination as follows: the tortoise's back is black, and the tortoise divination is to let the tortoise go to the underworld to ask his ancestors, bring back the answers and show them to the world in the form of divination. Therefore, the earliest Xuanwu is the tortoise. Since then, the meaning of Xuanming has been expanding. Turtles live in rivers, lakes and seas (including turtles), so Xuan Ming became a water god; The tortoise lives long, and Xuan Ming has become a symbol of immortality; It turned out that the underworld was in the north, and the divination of Oracle Bone Inscriptions in Shang Dynasty was' its divination will be in the north', so Xuan Ming became a northern god again.

Xuanwu, like other three spirits, is also derived from the 28 stars on earth: bucket, ox, female, air, danger, house and wall. However, people after ancient times have the following explanations for Xuanwu. Xuanwu' is a tortoise. "。 Volume 44 of Emperor Tai Shang Ru Zhai Yi calls North Xuanwu Star Jun: "Dou Su Tian Miao Xing Jun, Niu Su Tian Ji Xing Jun, Female Su Tian Nv Jun, Xu Su Tian Qing Xing Jun, Su Su Tian Qian Xing Jun, Su Su Su Tian Qi Xing Jun, Su Bi Shi Tianxing Jun". As for its image, Jiao Tong's Essentials of Daomen has seven clouds: "North Xuanwu, Taiyin Metaplasia, and Virtual Danger. "At the same time, Taoism also uses it in alchemy. For example, Volume 72 of Yun Qi Tanabata quoted the Dan of the Four Gods in ancient books and records as saying: "Xuanwu is the black mercury in northern China, which can be soft and firm. "The Classic says: Good is like water. Non-lead, non-tin, non-stone and the like, water is Hedong Shenshui, born before heaven and earth, so medicine can't be abandoned temporarily, and it can support everything, so it is called Xuanwu.

Xuanwu gained value in the Song Dynasty and was personified. This is inseparable from the help of the emperors of the Song Dynasty. In the early Song Dynasty, Zhenwu and Tian Peng were legendary generals in heaven. In the first year of Tianxi, something happened in the military camp. In "The Original" for seven years:' Someone saw a snake in the camp, and the sergeant built a real martial arts school because of it. In April of the following year, the spring was inexhaustible, and the sick people drank more. When Zhenzong heard this, he wrote a letter and built a scene there, named it' Xiangyuan'. This is probably the earliest Zhenwu Temple in China. It is often said by later generations that during the reign of Yang Di, the Jade Emperor became one of his three souls, Empress Lezheng, tired of the world, abandoned Wudang Mountain for practice, and successfully ascended to heaven, defended the north and lived in Xuanwu, posthumous title.