Many-Treasures then calls Sakyamuni to join him inside the stupa, offering him half of his seat. Thus Many-Treasures and Sakyamuni sit side by side, sharing the same seat.

Since the seat of the two Buddhas is too high for the congregation to see, Sakyamuni raises them up into the sky by his supernatural powers. Then he says to them, “I shall soon enter into Nirvana. Is there anyone here who is willing to expound the Lotus Sutra in the world after my extinction? I wish to hand it on to someone so that it can be perpetuated” (p. 187).

This statement is followed by verses explaining how difficult it will be to expound the Lotus Sutra after his extinction.

He lists nine examples of unimaginable difficulty, and then stresses in six articles that those hardships are nothing compared to the demanding mission of his followers. The first part of the teaching is as follows:

It is not difficult to expound all the other sutras, as many as there are sands in the River Ganges. It is not difficult to grasp Mount Sumeru and hurl it to a distance of countless Buddha worlds. It is not difficult to move a world composed of one thousand million Sumeru-worlds with the tip of a toe and hurl it to another world. It is difficult to expound this Sutra in the evil world after my extinction (p. 190-1).

[T]he place where the Sutra is delivered will be changed at the beginning of the next chapter. Up to and including this chapter, the Buddha has been speaking on Mount Sacred Eagle, near the city of Rajagriha. After a mysterious phenomenon takes place at the beginning of Chapter Eleven, and continuing until Chapter Twenty-two, his sermon will be delivered around a treasure tower (stupa) which is hanging in space. Since that part of the sutra is delivered from this new location, the section from Chapters Eleven to Twenty-two is referred to as the “Assembly in Space,” or “Assembly in the Sky.” The scenes before and after the assembly in the sky are called respectively, the “First Assembly on Mt. Sacred Eagle” and “Second Assembly on Mt. Sacred Eagle.”

The studies conducted over so many centuries made possible a deeper understanding of the Lotus Sutra, and methodological standards for its interpretation were established. One example is called Kamon. It is a classification of the twenty-eight chapters into several sets for a systematic explanation of their meaning.

The major Kamon is the “Three Parts of Each of the Two Divisions of the Lotus Sutra” which was established by Great Master Chih-i. Most commentators since his time have accepted his guidelines. …

[T]he “Three Parts of Each of the Two Divisions of the Lotus Sutra” refers to the division of the Sutra into two main sections: the first half, consisting of Chapters One through Fourteen, and the second half, consisting of Chapters Fifteen through Twenty-eight. Kamon gives a detailed explanation of the reason for this division. The first half is named Shakumon, literally “imprinted gate.” Its main purpose is to teach how “hearers” and Pratyekabuddhas can attain Buddhahood in the One Vehicle. The second half is called Hommon, which means “Primal Gate” or “Primal Mystery.” This part reveals Sakyamuni to be the infinite, absolute Buddha, the Buddha who attained enlightenment in the remotest past but still leads living beings in the present. These two points are considered the fundamental ideas of the Lotus Sutra.

In [Chapter Eleven, Beholding the Stupa of Treasures], the cosmos is so sublimely depicted that we feel as if we are seeing a drama in space. This majestic picture is a symbolic representation of the ideal world of the Lotus Sutra.

[T]he Sutra says that innumerable Buddhas or duplicates of Śākyamuni in the worlds of the ten directions were assembled in one place. Each of the duplicates can be seen as a manifestation of Śākyamuni himself, who took the forms of other Buddhas in order to expound the Dharma in other worlds. Now they were all assembled in one place, meaning that all the Buddhas throughout space were unified at that moment by the one Buddha Śākyamuni.

Let us go back for a moment to the Stupa of Treasures. Ordinarily a Stupa is a mausoleum where the relics (ashes) of Sakyamuni are enshrined. Once Sakyamuni is extinct, living beings can worship him only in his relics. The Sutra says that Many-Treasures Buddha will appear whenever and wherever the Lotus Sutra is expounded. This means that the living Sakyamuni, represented by his relics, and the Lotus Sutra are united as one single entity.

Great-Eloquence Bodhisattva wants to see Many-Treasures for himself, and he makes his desire known to Sakyamuni. The Buddha replies:

Many-Treasures Buddha made another great vow: “If any Buddha wishes to show me to the people when my Stupa of treasures appears before him so that I may be able to hear the Lotus Sutra, all his duplicate Buddhas in the worlds of the ten directions must be recalled. Then I will show myself before the people.”

Then Sakyamuni emitted a ray of light from the white curls between his eyebrows. The ray of light illumined the east, where the people saw innumerable Buddhas of innumerable worlds. Illuminated by the ray of light, those Buddhas of the worlds of the ten directions came pouring into the World of Endurance (our world) to make offerings to Sakyamuni Buddha and Many-Treasures Tathagata. At that moment, the World of Endurance was purified. The ground of the world became lapis lazuli; the roads were marked off by golden ropes; all cities, rushing torrents, and mountains (barriers which divide people from each other) were eliminated. Each of the arriving Buddhas was accompanied by an attending Bodhisattva. They all came to the purified World of Endurance, and sat under jeweled trees on lion-like thrones. All the thrones in the one thousand million Sumeru-worlds (inhabited worlds) were too few to accommodate so many Buddhas, so Sakyamuni purified two hundred billion nayuta [one nayuta is one hundred thousand million] other worlds to receive them. Still there was not enough room for them all, so Sakyamuni purified two hundred billion nayuta more worlds in eight directions of space to receive them (p. 183-4).
This is called the “triple purification of the worlds.”