hmm jhana is a means to get to the sukha. Corruptions of mind are what doesn't allow you to live without blemish and comfortability. Jhana doesn't allow corruptions to arise.
jhana could mean escape literally, you seclude yourself from hindrances so that sukha could arise.
that above Sutta inlcudes the knowledge and vision, it is after 4 jhanas.I developed immersion while placing the mind and keeping it connected; without placing the mind, but just keeping it connected; without placing the mind or keeping it connected; with rapture; without rapture; with pleasure; with equanimity. So kho ahaṃ, anuruddhā, savitakkampi savicāraṃ samādhiṃ bhāvesiṃ, avitakkampi vicāramattaṃ samādhiṃ bhāvesiṃ, avitakkampi avicāraṃ samādhiṃ bhāvesiṃ, sappītikampi samādhiṃ bhāvesiṃ, nippītikampi samādhiṃ bhāvesiṃ, sātasahagatampi samādhiṃ bhāvesiṃ, upekkhāsahagatampi samādhiṃ bhāvesiṃ.
When I had developed immersion in these ways, Yato kho me, anuruddhā, savitakkopi savicāro samādhi bhāvito ahosi, avitakkopi vicāramatto samādhi bhāvito ahosi, avitakkopi avicāro samādhi bhāvito ahosi, sappītikopi samādhi bhāvito ahosi, nippītikopi samādhi bhāvito ahosi, sātasahagatopi samādhi bhāvito ahosi, upekkhāsahagatopi samādhi bhāvito ahosi.
the knowledge and vision arose in me: Ñāṇañca pana me dassanaṃ udapādi,
And what is the way of developing immersion further that leads to gaining knowledge and vision? Katamā ca, bhikkhave, samādhibhāvanā bhāvitā bahulīkatā ñāṇadassanappaṭilābhāya saṃvattati?
It’s when a mendicant focuses on the perception of light, concentrating on the perception of day, Idha, bhikkhave, bhikkhu ālokasaññaṃ manasi karoti, divāsaññaṃ adhiṭṭhāti—
regardless of whether it’s night or day. yathā divā tathā rattiṃ, yathā rattiṃ tathā divā.
And so, with an open and unenveloped heart, they develop a mind that’s full of radiance. Iti vivaṭena cetasā apariyonaddhena sappabhāsaṃ cittaṃ bhāveti. This is the way of developing immersion further that leads to gaining knowledge and vision.
Ayaṃ, bhikkhave, samādhibhāvanā bhāvitā bahulīkatā ñāṇadassanappaṭilābhāya saṃvattati.
it can't be that hard? teh thing you can do after 1-4 jhana is you can do have perception of said thing on where it doesn't exist naturally. And eventually wisdom, knowledge and vision rises.
I think the logic is in order to have perceptions of kama-loka you need be dwell in rupa-lokadassanaPTS Pali-English dictionary The Pali Text Society's Pali-English dictionary
Dassana，（nt.） [Sk．darśana，see dassati1] -- 1．Lit．seeing，looking； noticing； sight of，appearance，look．Often equivalent to an infinitive “to see，” esp．as Dat．dassanāya in order to see，for the purpose of seeing （cp．dassana-kāma=daṭṭhu-kāma）：[Bhagavantaṁ] dassanāya M.II，23，46； A.I，121； III，381； Sn.325．-- （a） （nt.） “sight”
just that these samadhis won't take into account that there is unborn tendencies, anusaya, which are removed with other type of samadhibhavana.