SN15.5 — The Mountain Discourse
He was dwelling at Sāvatthī ... in the monastery ...
Then a certain disciple approached the Blessed One; having approached, he paid homage to the Blessed One and sat down to one side. While sitting to one side, that disciple said to the Blessed One:
How long, venerable sir, is an eon?
An eon is long, disciple.
It is not easy to count it as so many years, or so many hundreds of years, or so many thousands of years, or so many hundreds of thousands of years.
Can an analogy be made, venerable sir?
An analogy can be made, disciple, the Blessed One said.
Suppose, disciple, there was a great mountain of solid rock, one yojana long, one yojana wide, and one yojana high, without any cracks, without any holes, a single solid mass.
At the end of every hundred years, a man would stroke it once with a piece of fine cloth from Kāsi.
That great mountain, disciple, would be worn away and eliminated by this effort more quickly than an eon.
Such is the length of an eon, disciple.
And many such eons, disciple, have been spent, many hundreds of eons, many thousands of eons, many hundreds of thousands of eons.
Why is that?
Because, disciple, this cycle of rebirths is without discoverable beginning.
A first point ...
Therefore, disciple, it is enough to become disenchanted with all formations, enough to become dispassionate, enough to be liberated.