Free From Activity: A Teaching From Ajaan Mun

Activityless-ness is the end point of the world, beyond supposing and formulation.

saccanam caturo pada
khinasava jutimanto te loke parinibbuta

The four Noble Truths — suffering, its cause, its cessation, and the path to its cessation — are activities in that each truth has an aspect that has to be done: Suffering has to be understood, its cause abandoned, its cessation made clear, and the path to its cessation developed. All of these are aspects that have to be done — and if they have to be done, they must be activities. So we can conclude that all four truths are activities. This is in keeping with the first verse quoted above, which speaks of the four truths as feet, stair treads, or steps that must be taken for the task to be finished. What follows is thus termed activityless-ness — like writing the numerals 1 2 3 4 5 6 7 8 9 0, then erasing 1-9, leaving just 0, and not writing anything more. What is left is read as 'zero,' but it doesn't have any value at all. You can't use it to add, subtract, multiply, or divide with any other numerals, yet at the same time you can't say that it doesn't exist, for there it is: 0 (zero).
This is like the discernment that knows all around, because it destroys the activity of supposing. In other words, it erases supposing completely and doesn't become involved with or hold on to any supposings at all. With the words 'erasing' or 'destroying' the activity of supposing, the question arises, 'When supposing is entirely destroyed, where will we stay?' The answer is that we will stay in a place that isn't supposed: right there with activityless-ness.
This explanation is in line with the aspects of reality that appear clearly only to those who practice, and that people who don't practice can't know. Only when we listen and then practice accordingly until we see and know of our own accord will we be able to understand.
The meaning of the next verse is this: 'Those who have no more effluents extinguish the three realms and are dazzling.' In other words, they have practiced persistence and made an investigation 'bhavito bahulikato.' In other words, they have worked at it and developed it repeatedly to the point where the mind has the strength capable of analyzing and destroying all supposings so as to reach activityless-ness. They can thus gain release from the three realms.
In extinguishing the three realms, arahants don't fly up into the realms of sensuality, form, and formlessness. They stay right where they are. The same was true of the Buddha: When he extinguished the three realms, he was sitting in one spot, under the Bodhi tree. He didn't fly up into the three realms. He extinguished them at the mind — for right there in the mind is where the three realms exist.
Those who aim at extinguishing the three realms should thus extinguish them in their own hearts. Only then will they obliterate activity — the act of supposing — from the heart, leaving just activityless-ness. This is the primal heart, the primal Dhamma, which knows no death.