Chapter 16, responding to the perplexity of people in chapter 15, explains that Shakyamuni Buddha is really the Everlasting Original Buddha using the metaphor of the five hundred dust particles worth of eons. Suppose someone ground into fine dust five hundred thousand billions of myriads (nayuta) of countless (asaṃkhya) three-thousand great thousandfold worlds, and just one particle of this dust was deposited on every five hundred thousand billions of myriads of innumerable lands until all of the dust was exhausted, and then all of these worlds, those with a particle of dust and those without, were ground into dust. If one particle of dust is regarded as equivalent to an eon, the period of time equivalent to all of the dust particles is nowhere near as long as it has been since Shakyamuni became a buddha.

An eon is a long time. A nayuta is usually taken to mean one hundred billion. The word asaṃkhya means an uncountable number. And “three-thousand great thousandfold worlds” refers to the result of adding together three kinds of thousandfold world—small, medium, and large. It is said that a small thousandfold world corresponds to the solar system, a medium one to the galaxy, and a large one to a nebula. In chapter 7, there is a story in which one of these three-thousand great thousandfold worlds is ground into particles of dust and one particle is deposited on every thousandth world. It is called “the parable of the three thousand dust particles of eons.” In short, the story emphasizes the Buddha’s eternal life by means of these similes of very large numbers.