Ok, thanks for describing for me some of your "no-self realization" and prior teachers. I also found and read Siddhartha in high school (it was one of the English-language books the school library had amid a slough of existential works.)
In zen teachings maybe your no-self realization might be labeled a kensho experience - sort of a fast, jarring insight moment that does change the mind of the practitioner. One starts to experience less contrivance of daily life because some contrivances of personality evaporate/reduce.
So, if your no-self realization is such a kensho moment, then afterwards the practitioner
may naturally feel a growing urge to attend closely to the practice. It is as if mind is ready for --- or nearly ready for ---- focus.
"Nearly" because, there's usually a shit-hits-the-fan moment preceding attraction to concentration and natural willingness to focus attention and to watch one's mind calmly. For example, a no-self realization can naturally feel very gratifying: its spacey equanimity, its freeing detachment. The space and detachment and wonder naturally feel like a relief when one thinks about how rocky things were as a self-dominating persona. So, that space and detachment are gratifying until some natural curiosity starts to come through, "Is this all there is?" That's a subtle tension/dissatisfaction that grows, until it becomes a bona fide stress. The shit usually hits the fan because the mind demands that that tension not be ignored, the mind really wants to know, "Is this it? and if so why do I not feel enlightened?" So, one goes from spacey, detached, wonder-drifting to some big "dammitall!" moment (maybe an eruption with a person or a banging the thumb in the car door kind-of thing).
That "dammital" (or eruption/stress/frustration) is also a kensho experience. It's an jarring insight into the incompletion of the non-self realization, for example. After this, the mind turns itself towards patient zazen.
That willing patience to just sit is the very beginning of concentration.
So, back to this:
is there any insight in which I can reach stream entry through contemplation or is it something that needs to be done through grounding the physical body first?
If a person has a rope in a bad knot, they will usually apply a few approaches to getting it undone. Maybe there's first closely looking and trying to push the ropes ends back through certain loops, then maybe there's just rubbing the knot between the fingers to loosen everything at once, then maybe there's plucking the knot with fingernail tips, and so forth. So, that's my long way of saying: both.
You note you are "much more engaged by a zen like approach". So, koan can be used with zazen. This would give you both a mental object (e.g., "Who am I?") and a physical practice (zazen).
For example, if you put yourself in a seven-day sesshin, you could repeat "Who am I?" When the knees ache, "Who am I?" When the rhombus muscles are sore, "Who am I?" When falling asleep, vigorously, "Who am I?" When stomach growls before oryoki, "Who am I?" When first food hits tongue and there is pleasure-gratification of eating, "Who am I?" When there is the urge to eat faster, "Who am I?" When there is the chore to do, "Who am I?" When there is the urge to determine a part of the chore is done adequately, "Who am I?" When there is irritation towards the body-actions of another practitioner, then "Who am I?" When the mind and body begin to settle, "Who am I?" When there is excitement over a mental object/state,"Who am I?"
Koan, however, can be a very frustrating practice. Koan can build mental tension while body has its own intense zazen tension: this can become a ceaseless round of frustrations and pains, with angry/sad/maddening eruptions. Indeed, part of koan is to build some tension and cause letting go. I think it takes a great teacher to work with their student closely in just koan and zazen, especially. When I consider some of the waiting periods people have weathered at the entrance ways of zen monasteries, it occurs to me that the monastery is seeing if the practitioner has already learned some calm in the face of massive frustration and tension. Heck, there's a lot of non-ideal stuff in ideal-looking zen monasteries, so the Roshi has to see how the applicant's mind is or is not already well-tempered. I also consider the
marathon running of novice monks: burning off tensions, exhausting the body and mind, helping the novice get to a cleared mental base quickly (through physical exhaustion and terrain that demands mental focus). So, since you have chosen to use the word "stream-entry", and this concept falls within Theravadan practices, you can also switch your study framework for a while. For example, anapanasati builds concentration in a very pleasant physical training ground. As the mind and body progress, the instructions become more refined; the mind learns in friendly circumstances to seclude itself into simpler conditions, weaning itself naturally off of pleasure into a concentrated equanimity. And, when frustrations grow, one still has access to lots of innocent pleasure just by breathing in (and this, in turn, contributes to naturally growing patience when off the cushion).
Also, as concentration builds in this friendly training arena of anapanasati, then you could take up zazen as you know it and you could read Venerable Analayo's book "Satipatthana: the Direct Path to Realization" (Windhorse, 2003) to provide a contemplative structure outside of your sits.
So, I raise anapansati and satipatthana because you are looking at a concept (stream entry)
that is housed in the Pali canon and
addressed well by Theravadan approaches.
I've thrown a lot out here. What are your thoughts?
[Edit: there are other practices (e.g., Tibet-source practices, advaita, mysticism) around here, too, however, since this is a practice forum people may need to see what practice you are doing before than can share their own experiences/questions. So, another way to flow into what you may get out of being on this site, could be your commenting in other threads. This is a way some people practice: indeed it was the way I came to see what "I" was doing here -- first, by seeing my own attraction and aversion to what was already out there and reacting to it.
By being here, it seems that your no-self realization is naturally starting to look for some anchorage, knowing that some practice/insight is needed to bridge no-self realization and your interest in these ideas "stream-entry"/"enlightenment".]
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