In the Buddhist system of timescale, the word “kappa” meaning “cycle or aeon” is used to denote certain time-periods that repeat themselves in cyclical order.
Four time-cycles are distinguished;
a great aeon (maha-kappa),
an incalculable aeon (asankheyya-kappa),
an included aeon (antara-kappa) and a lifespan (ayu-kappa).
2. Great Aeon or World Cycle (Maha-kappa) A maha kappa or aeon is generally taken to mean a world cycle.
How long is a world cycle?
In Samyutta ii, Chapter XV, the Buddha used the parables of the hill and mustard-seed for comparison:
• Suppose there was a solid mass, of rock or hill, one yojana (eight miles) wide, one yojana across and one yojana high and every hundred years, a man was to stroke it once with a piece of silk.
That mass of rock would be worn away and ended sooner than would an aeon.
• Suppose there was a city of iron walls, one yojana in length, one yojana in width, one yojana high and filled with mustard-seeds to the brim.
There-from a man was to take out every hundred years a mustard-seed.
That great pile of mustard-seed would be emptied and ended sooner than would an aeon.
How long in time has been the succession of aeons in the past?
According to the Buddha: “So long, brother, is an aeon. And of aeons thus long more than one has passed, more than a hundred have passed, more than a thousand, more than a hundred thousand.
How is this?
Incalculable is the beginning, brother, of this faring on.
The earliest point is not revealed of the running on, the faring on, of beings cloaked in ignorance, tied to craving.”