Vipassana is insight meditation. When it comes down to it, in vipassana we are looking at things to determine the nature of things:
1. Do they change? If they do, they’ll disintegrate and die, sooner or later – so it’s not true because it can’t stand up to destruction.
2. Do they not change? If you find something does not change – then it will never change and therefore will never disintegrate or die. Even if you wanted to try to make it disintegrate and die out – it won’t. So that’s how you can see its true nature – being able to stand up to destruction.
Here, Ajahn Maha Boowa explains vipassana in terms of investigating the 5 skandhas/khandhas using these principles:
Alright! If the citta is ruined by the investigation, let it be so. Don’t cherish and cling to it. If the citta stands up to the truth, it will remain and won’t disintegrate.
If it stands up to its true nature, it will be free from the corruptions and so arrive at the state of purity. Let’s see whether the citta will be annihilated or not. Dig into
it. Don’t cherish anything, not even the citta. Don’t be afraid that the citta will be destroyed or dispersed or vanish.
Once paññã has completely wiped out the infiltrators, every kind of kilesa will disappear for they are all the falsity existing within the citta. When the investigation really gets moving properly, those things that are vulnerable to dispersion will not be able to withstand; they will disintegrate. But the nature that cannot be annihilated under any circumstances, will always remain. How could this citta disappear?
Please notice that it is the citta that is dominated by the kilesas. Once paññã has totally shattered and cleared the kilesas away, the citta will be transformed into the state of purity. This is the genuine purity. How can it vanish? Were it to disappear, how could it be pure?
Everything else dissolves and disintegrates, but this one is the genuine amata (the Undying). It is deathless by way of purity. This is not the amata that spins with the vatta cakka (the revolving wheel of birth and death). The other is called the undying, but it also whirls with the vatta cakka . This amata is undying and does not revolve. It is vivatta —undying and non-revolving. This is the real and true essence existing in the midst of our khandhas.
This is indeed the main culprit, the one that incites and agitates the citta, fooling it to be deluded by the world and the dhãtu (elements), by the khandhas and the various vedanã, and by pain, illness, confusion and madness. In truth, these things voice no opinions.
Whatever the body is, that’s what it is. When vedanã arises, it does so in its natural way. It does not know that it is vedanã, that it is dukkha or sukha or neutral or whatever. It is this citta that forms the opinions and ideas about them and then falls for its own opinions and ideas, gaining no benefit but only afflicting itself with much harm.
We must therefore investigate them with paññã to see according to their true nature.
What will then disintegrate? What have we got to lose? If the body should
break, let it break. It is anicca, dukkha and anattã, as the Lord always said. These dhammas reign over the entire physical world, so why shouldn’t they rule over the khandhas? If it falls under the laws of anicca, dukkha and anattã, how can we interfere? Let go of it! If it can’t withstand, let it break! Everything in this physical world is breaking and dissolving. Some sooner, others later, but surely our khandhas can’t last for eons and eons for they fall under the same laws and limitations. So let’s investigate to see according to truth before they break up. This is circumspect paññã. Let’s get to comprehend clearly when dukkha vedanã appears.
p21-23 Amata Dhamma by Ajahn Maha Boowa