"The sahā world Shakyamuni Buddha revealed in the “Life Span” chapter is the eternal pure land, impervious to the three calamities and to the cycle of the four kalpas. The Buddha neither has entered into extinction in the past nor will be born in the future. And the same is true of his disciples. This means that their lives are perfectly endowed with the three thousand worlds, that is, with the three realms of existence*."
*The Realm of the Individual, the Realm of the Society of Beings, and the Realm of the Environment.