Have been reading on the site for a while. Ready to add some data points from my samatha + vipassana practice. Writing here will hopefully also help in extracting further insights from my practice and provide a chance to learn from other dho folks. I am about to start into the MTCB so hopefully will be able to better relate my experiences to those following that material soon. I'd like to get a baseline out there for my practice before being too influenced by that material so that I can use it to confirm or challenge my current practice.
Would consider myself a mid level practitioner. Rupa jhannas are reliably stable and accessable under reasonably favorable conditions in soft, hard, and momentary varieties. Piti is very noticeable in the background off cushion throughout the day as little blips and spikes. Sukkha also present, although usually requires more focused concentration to pick apart from beneath the piti. With application of noting vipassana, equanimity can also surface for some time under good conditions.
Session was in late evening, which has been a relatively challenging time to practice. Access concentration is second nature now, so discursive thought is silenced quickly. First nimittas to appear are the "Headlight" type, one for each eye. After turning attention from the breath to these, the nimitta shifts to a familiar single ring / event horizon at the center of vision. This appears as an afterimage like from a camera flash. It alternates between a bright ring surrounded by a dark background and a dark ring surrounded by a light background. I try a short exercise of trying to move the nimitta around my field of vision but this quickly begins to cause eyestrain and headache as the nimitta dissolves and reforms a couple of times, so I stop.I should note here that I am not especially good at using visual nimittas as a concentration object. I was first able to achieve jhanna using the Leigh Brasington method of "Feeling" for momentary piti. I did not notice nimittas while doing this, but later read about them and wondered if jhanna would be any different using them. After working on the visual nimitta method, I was able to achieve jhanna using it, but still found it more difficult than just feeling for momentary manifestations of jhanna factors. After I worked with the visual nimitta method, nimittas and momentary piti tended to arise simultaneously, so my working assumption is that they are two representations of the same thing and using either as a transitional meditation object is valid.
piti/kundalini which is present throughout the day has settled down as it normally does by this time of the evening. It's noticeably centered in the lower spine and back and takes some extra coaxing to extend to the whole body. Eventually it happens, but still noticeably pacified relative to daytime practice.
a good bit of concentration was required to reach the tipping point where the piti/sukkha feedback loop becomes self sufficient. Now I relax into it. I have set the intention at the beginning of this session to drop briefly into noting vipassana to deal with hindrances as necessary. I label "Tired" a few times and move my focus back into the jhana state. Piti and sukkha suffuse the body, but it is a gentle rocking sea of bliss rather than the heavy, crashing breakers that are typical in daytime practice. Still, there is some raggedness of breath and mild shaking, which does not distract. Unlike during the day, heavy absorption doesn't typically ripen in 2nd unless I spend quite a bit of time here. At this point I would consider the state to be "Neighborhood" or light jhana rather than a full absorption (Ajahn Brahm would not consider this a "Real" jhana, although my own reading of the canon material seems to contradict the idea that only super heavy jhana counts). I opt to continue to the next jhana.
as usual, sukkha seems to be layered beneath piti. I focus attention on letting go of piti. Sukkha becomes the predominant factor, but it too is subdued relative to daytime practice. I am left with a lukewarm afterglow, like sitting on the beach as the sun starts to set and the air begins to cool. Sukkha seems especially hard to hold onto as a meditation object and this state requires more focus to maintain and proceed through. Focus can momentarily dissipate or sidetrack or stall here if I get lax. This jhana is also the first in which what I would call as yet unrealized/potential thoughts become perceptable. This is an interesting phenomenon where it seems to be possible to be aware of the seeds of thoughts rising up out of seemingly nowhere and passing beneath consciousness. If focus remains tight on the meditation object, they mostly just pass by without being "Realized" into what we would conventionally call consciousness. Yet it is possible to sense the gist of the content without it being fully realized into consciousness. My theory is that in practicing non-jhana vipassana noting we make ourselves sensitive to the gist of some of these thoughts that previously went uncontrolled into consciousness in time to prevent them from being realized and causing further cascades of realized "thought seeds." A hypothesis is that this is very close to the idea of the "mindstream" in Vajrayana doctrines, though this has yet to be confirmed. If that is so, observing carefully should provide some very interesting insights into the topics of no self, dependent origination, and possibly even rebirth.
sukkha is surrendered. The first thing noticed is a sense of a level shift, "Dropping down" a level of excitement/stimulation accompanied by some very neutral mental vibration and soft light. There is a momentary resistance at the 3rd-4th transition where the ability to observe the thought seeds seems to peak, and then that is broken through. Up to this point, hearing is the least attenuated sense. Then there is a noticeable downshift in the signal relative to noise. This causes a very noticeable rise in "White noise" relative to sounds perceived by the ear. I have noticed that the deeper the absorption in 4th, the more this is the case. I take a moment to stabilize and go deeper here. Unlike 1st and 2nd jhanas, the ability to absorb in 4th does not seem to decline much with the time of day. Relaxing into the jhana, I feel the remaining, distant sense doors greatly attenuate. What was the center of the body feels as though it no longer exists. Sense contacts that remain are all on the outside of the body. I read in a previous post (David?) that perception becomes "doughnut shaped" and I think that is an apt description. If you were to draw a ring (Like the ring nimitta) around the body, the perceived intensity of sense contacts in space would be strong along the ring and weak to non existant inside it. Coming back to the nimitta is interesting because the lights often go into crazy firework mode in deep absorption in this stage, although tonight they do not. Looking to the breath it seems incredibly, impossibly shallow or even undetectable. Looking at the self, there is a collection of sense contacts and the aggregates that have formed around them: comparisons with past and (imagined?) future states, aversions, and attachments, which are themselves aggregates. Looking for the thought seeds, they are there but there is no suppression because none of them are passing into consciousness. They seem beneath concern in this jhana. More than the preceding jhanas this one feels extremely sturdy and stable. There is noticeable resistance to coming out of this state and it seems sort of metastable, requiring a serious push to leave in any direction. Even one-pointed thought experiences some drag to stay in 4th. It locks on tightly and effortlessly to equanimity.
at the beginning of the meditation I set an intention to stretch myself to work with the boundless space arupa jhana. I have tried to work with this jhana in the past by focusing on expanding equanimity into infinity. This time the focus was on equanimity and then on to the "Doughnut" of remaining sense contacts and associated aggregates. I began trying to push the doughnut out, with the sense contacts remaining on the outside. There was resistance, which was overcome by a few attempts at doughnut expansion, then a sense of the ring becoming more distant. This exposed a subtle clinging to self-identity as there was a moment of vertigo, slight sense of panic, and then a sort of inversion in perspective where instead of perceiving the ring expanding outward, a core of subtle self identity revealed itself and was perceived as shrinking to insignificance and then nothingness in the center of the ring. This is interesting as I do not believe the jhanas beyond the 4th are supposed to be important for awakening, yet this seems like an important insight. Clearly more work is to be done and I will need to continue to work with and understand this jhana, or else address the underlying problem in some other way. Unless what just happened was enough. Next trip into the 5th jhana will tell.
I had a more detailed narration that was unfortunately lost while trying to submit, so will just put down the highlights. Proceeded as before to 5th jhana. Pushing the residual sensory doughnut outward led to the same unpleasant feelings/aversion, but less intense this time. The kernel of self identity appeared in the center of the doughnut as before when it was expanded. Focusing on the kernel led to a near instantaneous expansion of an all pervading, unchanging neutral luminosity. On close examination those remaining peripheral sense aggregates seemed to have become very much more insubstatial than before although I was not able to identify exactly what had been lost. Possibly the central kernel are the mental aggregates and by focusing on them I was touching on the 6th jhana / infinite consciousness? Given how slippery the jhanas are I'm not willing to draw that conclusion based on a single experience. I'm also wondering whether it is expected to have this sort of ghostlike remnant of peripheral sense aggregates remaining this far into the jhanas or whether I am not doing a complete enough job of establishing the jhanas. Will need to read more to see.
As an independent practitioner, I have made a point of avoiding reading any detailed descriptions of the jhanas (Beyond the name) until I think I might have entered them. This is my best attempt to avoid deluding myself into a "constructed" jhana. It's also because I was trained to be a skeptic and I want to have some kind of confidence that the whole thing is not just an exercise in clever suggestion. So I run an experiment. My method has been to wait until I have attempted to let go of the current object of meditation, either directly or by shifting focus to some phenomenon that seems important, go where that takes me, record what happened, and only when I am reasonably certain a fundamental shift has occured begin to read the description of the next jhana.After last night I decided to read the MCTB description of the 6th, the first time I have done this. And wow, I couldn't have asked for a description much more spot on to my experience, especially the strange all pervading neutral luminosity so different from the nimittas or other things I have experienced in the jhanas. So I have to admit, my skepticism has taken another body blow here.