Advanced Jhana Classification, by Daniel M. Ingram

Here is a proposed method of classifying the jhanas that is more sophisticated and flexible than the original simple classification system found in the Pali texts and commentaries. It is basically the system I use in my head, and yet I realized that I haven't written it down anywhere in quite this fashion. I hope that one day something like this system is converted to something more secular, such that it can serve as a technical shorthand or language for discussing meditative attainments in general. Until then, here goes with the serious geekery:

The basic building blocks of the system are the jhanas, which briefly noted are as follows:

1. First Jhana: involved narrow attention, sustained effort 2. Second Jhana: involved slightly wider attention, more motion of objects, and is significantly more effortless 3. Third Jhana: involves wider field of attention with center of attention out of phase, and has distinct phase problems in general 4: Fourth Jhana: involved more naturally spacious attention and has a much more balanced sort of attention than the previous ones 5: Boundless Space: a byproduct of noticing the spacious aspect of the 4th jhana 6. Boundless Consciousness: a byproduct of noticing the conscious aspect of the 5th jhana 7. Nothingness: like the 3rd jhana version of the formless realms in that it is like Boundless Space except that the phase of attention is tuned to anything but that and also not to anything else, so it notices that there is nothing there in that space, sort of like the advanced phase problem version of 3rd jhana taken to an extreme 8. Neither Perception Nor Yet Non-Perception: what happens when you detune even from the already very strangely off-tuned 7th jhana and don't even notice that: the pinnacle of phase out-ed-ness without even attention to that

Add to this the notion that these 8 jhanas can fall on a continuum from hard to soft, meaning that you can be really, really into the jhana or in a softer, less absolute version of that same territory that is still different from what I will loosely call "ordinary" consciousness, whatever that is, and yet not in it as hard as is possible. This falls into shades of grey.

Add to this that these 8 hard or soft jhanas can also be more analog or digital, more smooth or vibratory/fluxy, and thus there is an axis of development that relates to how samatha or how vipassana they are, how concentration heavy or how insight heavy, how seemingly stable vs how discontinuously they are perceived.

Add to this the notion that you can actually be in a sub-jhana aspect of them