According to Kamon, which is an ancient method of analyzing the Lotus Sutra, the first half of the Sutra, consisting of fourteen chapters, is called Shakumon—teachings “derived” from a source (shaku literally means “footprint; mon is “gate”). The second half, consisting of the final fourteen chapters, is known as Honmon or Hommon—the “Primary Gate” or Primary Mystery (hon means “root” or “source”). This second half reveals the Original and Eternal Buddha (Kuon Hombutsu). The appearance of the Bodhisattvas from Underground (Jiyu-no-bosatsu, literally “Bodhisattvas who well up from the earth”) is an introduction to the second half of the Sutra; and the next chapter, “The Duration of the Life of the Tathagata,” is its principal part.

That is to say, [Chapter 15, The Appearance of Bodhisattvas from Underground] presents the ideal Bodhisattvas in the persons of the Bodhisattvas from Underground. The following chapter, the “Duration of the Life of the Tathagata,” reveals the true nature of the Buddha (the Original and Eternal Buddha) and his true Pure Land. It is none other than this Saha-world of ours. Thus the “Duration of the Life of the Tathagata” will emerge as the Sutra’s heart and center.