My not-so-very-informed answer on this is that each nana is "like an emphasis on a linear stream of vipassana progression" within its respective
vipassana jhana.
- 1-3 nana are each an emphasis on a certain aspect of a layer of mind called the first vipassana jhana and the first nana corresponds to the first samatha jhana.
- 4th nana is in itself a layer of mind called the second vipassana jhana and it corresponds to the second samatha jhana.
- 5-10 nana are each an emphasis on a certain aspect of a layer of mind called the third vipassana jhana and the fifth nana corresponds to the third samatha jhana.
- 11th nana is in itself a layer of mind called the fourth vipassana jhana and it corresponds to the fourth samatha jhana (of which there are four stable "mutations", called the four formless jhanas. There are other mutations - basically you can mould the fourth samatha jhana in many ways. There is also something called Pure Land/Suddavasa jhanas, but I have yet to read and understand the theory of that).
These layers of mind have an axis going not only up/down but also in/out. You move up/down when doing vipassana. You move in/out when doing samatha. As you move in at each layer of mind, you access the respective jhana. As you move up the layers you progress through the
Stages of Insight.
Even more specific: The first nana is where the first samatha jhana is. The second and third nana are unstable aspects of the first vipassana jhana and so you don't really become absorbed in jhana there. Same thing goes for 5-10 nana, where the fifth nana is where the third samatha jhana is and 6-10 are unstable aspects of the third vipassana jhana, of which you can't become absorbed in.
20 Major Strata of MindTaking in jhanasThe Vipassana JhanasThe Samatha Jhanas(
The Progress of Insight)
Joshua L.:
...each progressively more non-dual with more mindfulness
What exactly do you mean, "more non-dual"?