That is one of the three supreme classics of the Daoists. According to Dao Lord Yuanyuan in the Great Thousand Universe, the three supreme classics originated from the ethereal upper realm.
The Taiji Theory practiced in the Tian Shi Jiao today is derived from the Taiji Scripture, but compared to the Taiji Scripture, it falls short by an incalculable margin.
"The Taiji Scripture!"
Chapter 554