After traveling through time, Xu Sheng carried a 'Book of Eternity' in his mind. Its function is that if Xu Sheng dies, he can be reincarnated into his best descendants ten thousand times.
Moreover, you can bring your memories, skills, and cultivation with you from your previous life. Xu Sheng's initial goal was to fully spread his bloodline and ensure his immortality.
Later, he learned that there really were fox demons in this world who repaid their kindness to scholars, some painted skins wandered around the world, some Taoist priests trained their bodies to become Yang gods and became immortals, and some monks abandoned their skins and sat down to become Buddhas...