I'm not nit picking you Mike, just sharing my current thoughts on this. Perhaps the notion that depth = intensity of cognitive black out at the five "external" senses is itself a problematic measuring stick to use.
What I find hard to swallow (I'll be honest, unbelievable actually) is the notion that the pinnacle of the path is a trance that is attainable with sufficient proficiency at manipulation of one's mental continuum, e.g. a technique devoid of insight. In the suttas we see, I think, different things leading to jhana, including faith, reflection on the dhamma, brahmaviharas, and some insight-type contemplations, the latter seemingly taking one as far as the 7th.
MN 106Aneñja-sappaya Sutta wrote:"Then again, the disciple of the noble ones considers this: 'Sensuality here & now; sensuality in lives to come; sensual perceptions here & now; sensual perceptions in lives to come; forms here & now; forms in lives to come; form-perceptions here & now; form-perceptions in lives to come; perceptions of the imperturbable: all are perceptions. Where they cease without remainder: that is peaceful, that is exquisite, i.e., the dimension of nothingness.' Practicing & frequently abiding in this way, his mind acquires confidence in that dimension. There being full confidence, he either attains the dimension of nothingness now or else is committed to discernment. With the break-up of the body, after death, it's possible that this leading-on consciousness of his will go to the dimension of nothingness. This is declared to be the first practice conducive to the dimension of nothingness.
"Then again, the disciple of the noble ones, having gone into the wilderness, to the root of a tree, or into an empty dwelling, considers this: 'This is empty of self or of anything pertaining to self.' Practicing & frequently abiding in this way, his mind acquires confidence in that dimension. There being full confidence, he either attains the dimension of nothingness now or else is committed to discernment. With the break-up of the body, after death, it's possible that this leading-on consciousness of his will go to the dimension of nothingness. This is declared to be the second practice conducive to the dimension of nothingness.
"Then again, the disciple of the noble ones considers this: 'I am not anyone's anything anywhere; nor is anything of mine in anyone anywhere.' Practicing & frequently abiding in this way, his mind acquires confidence in that dimension. There being full confidence, he either attains the dimension of nothingness now or else is committed to discernment. With the break-up of the body, after death, it's possible that this leading-on consciousness of his will go to the dimension of nothingness. This is declared to be the third practice conducive to the dimension of nothingness.
Can insight, and understanding, lead to jhana, rather than only the other way around? My current understanding is, yes.
This is not likely to be persuasive to anyone on a theravada board, so I hesitate to even say it, but in Chan and Tibetan Buddhism absorptive trances, while having their uses, are considered inferior to other approaches which emphasize the conjunction of insight and samadhi in the context of all six senses being wide open. We get the impression that "meditation" is not about modulating experience but rather about penetrating experience. Of course this is sometimes couched in obnoxious supercessionist rhetoric (e.g. this approach is superior to the hinayana absorptions) but perhaps those "hinayana absorptions" where never even that to begin with...
Or we might consider this off the wall idea from Ven. N. Nanamoli
I don't pretend to have any definite answers here, just thinking out loud. Thanks for listening!In other words, by understanding what jhāna is, one enters it, not by performing a set of prescribed motions that somehow make it “happen” to one.