Tongtian Hierarch's haughty words, it seemed, did make Sha Chen realize something. It turned out the Sage Laozi had ignored the Innate Earth because he sensed the presence of the Tongtian Hierarch. So, Laozi's persistent emphasis on taking disciples might not have been entirely about recruiting apprentices; it was more likely a test. He was probing to see if Sha Chen had already become a disciple of the Tongtian Hierarch. Had that been the case, Sha Chen likely would have used the Tongtian Hierarch as a shield.
