The realm of cultivating truth is divided into: refining qi, building a foundation, becoming an elixir (then an elixir), Yuan Ying, transforming spirit, refining emptiness, uniting, Du Jie and Mahayana. The finer ones are divided into early, middle and late. (such as the initial stage of gas refining. ) further fine stratification, 1~3 layer is the initial stage. By the way, the setting of each novel will be a little different. For example, refining gas, maybe the author wrote it skillfully, but most of it is like this.