At Sāvatthi.
Then, a certain bhikkhu approached the Blessed One. Having drawn near to him, he paid homage and sat down to one side. Sitting to one side, that bhikkhu said this to the Blessed One: “Venerable sir, how long is an |aeon::lifespan of a world system, a vast cosmic time span [kappa]|?”
“An aeon is long, bhikkhu. 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.”
“Then, is it possible to give a simile, venerable sir?”
“It is possible, bhikkhu,” the Blessed One said.
“Suppose, bhikkhu, there were city made of iron, a |yojana::a unit of distance used in ancient India, ranging from 3.5 to 15 km [yojana]| long, a yojana wide, and a yojana high, completely filled with mustard seeds, packed tightly into pellets or balls. At the end of every hundred years, a man would remove one mustard seed from the city. Sooner, bhikkhu, that vast collection of mustard seed pellets would be exhausted by this process, but not so an aeon. So long is an aeon, bhikkhu. And of aeons of such length, we have wandered through so many aeons, so many hundreds of aeons, so many thousands of aeons, so many hundreds of thousands of aeons.
For what reason? Bhikkhus, this |cyclic existence::wandering from one state of existence to another, the cycle of birth and death, moving on continuously [saṁsāra]| is without a discoverable beginning. A first point is not evident of beings who, obstructed by |ignorance::fundamental unawareness or misunderstanding of the true nature of reality, not experientially understanding the four noble truths [avijjā]| and fettered by |craving::wanting, yearning, longing, attachment, lit. thirst [taṇha]|, run on and wander in this cycle of existence. For such a long time, bhikkhus, you have experienced |suffering::discomfort, unpleasantness, discontentment, dissatisfaction, stress, pain, disease, i.e. mild or intense suffering [dukkha]|, |agony::intense suffering, anguish [tibba]|, and |calamity::disaster [byasana]|, the |cemetery::charnel ground [kaṭasī]| has been filled up with your bones. Therefore, bhikkhus, it is enough |to become disenchanted::to become disillusioned [nibbindituṃ]|, |to become detached::to become dispassionate [virajjituṁ]| and |to become free from::to be liberated from [vimuccituṃ]| |all conditions::all formations, all activities, all fabrications [sabbasaṅkhāra]|.”