Discrimination / Separation / Seclusion
Viveka has always had the meaning of "seclusion". But it is much more than that.
The gist of Buddhism is discernment (pañña) - pañña in its all encompassing meaning - and viveka is just about that.
Discrimination between the external (the khandhas of nāmarūpa of which we are fed,) and the internal, in satta. (see here, and here).
In other words, discrimination between the external and the internal. Separation from the external, and seclusion in the internal.
So "seclusion," yes! - but also "detachment". As in "discrimination" and "separation from" one of the components; before you go to "seclusion".
Breath is usually the start of it all, for it leads to building one's own feeling, devoid of the external. It helps one to discriminate between a purely "own" feeling, and a feeling coming from the external. The perception (sañña) of feelings (vedanā,) is a synergy called cittasaṅkhāroti (SN 41.6). And knowing the attributes/causes (nimitta) of this cittasaṅkhāroti is also discrimination. And the nimitta of one's own citta is one own's breath (kaya). [See SN 47.8 for an understanding of "picking up the nimitta of one's own mind (citta)"]. It is from the breath (as a yoni,) that you build (manasi-karoti) a feeling with the mind/mano (manasi).
Note that in SN 54.10 & 54.13, Buddha says: "I call this a certain kind of body, Ananda, that is, breathing in and breathing out". Also, in SN 41.6, the definition of bodily formations (kāyasaṅkhāro) are the immaterial in-breaths and out-breaths (assāsapassāsā); which, in satta becomes the (somewhat) material Ānāpāna, so to speak - (although one should consider while breathing, the all scope of kāya (as breath in this case) - the immaterial (cosmic) and the material)).
Note that kāya has quite a wide scope in Indian philosophy. It usually encompasses what the Vedic people used to call "the organs". Kā + ya means "what belongs to Ka" (where Ka is the other name for the God Prajāpati - the God made man - the all encompassing Self/self).
Therefore: काय Kaya = क Ka + ॰ईय -īya (iya forms possesives in Sanskrit).
So for instance, sakkāyadiṭṭhi means: Identity-view with Ka [aka Atta (Self)], as well as being one of his attas (selves). For Ka (prajapati wanted to be many). (Sakkāyadiṭṭhi = lit. beholding "with what belongs to Ka").
But let's go back to that kāya as breath:
One has forgotten what one's real citta is. One does not breathe consciously of his/her own breath anymore.
By breathing with awareness of this fact - and having build one's own feeling from one's own breath - one discriminates between the external feelings, and the internal one (one's own feeling).
This is viveka. This is discrimination, separation and seclusion.
Discrimination between the external & the internal - separation from the external - and then seclusion in the internal.
One is liberated by knowing his/her own citta (feeling - then perception of this feeling), through his/her own body (own breath/kaya) - liberation known as cettovimutti, when one does not cling anymore to the senses - but dwell in this free citta. And one is also liberated by this mere discrimination (paññavimutti) between the internal and the external - and the true process of arising and fading within oneself.
This is no picnic though. For the external will harshly reclaim its sanctuary in us.
That's a reality that not many of us want to face. But it is so.
And a true Buddhist should not tremble at that.
The Arahant to be, is the solitary sailor, fighting to cross the flood. And the elements are there to be contained. No easy task. Particularly when one remains a householder.
Viveka [fr．vi+vic] detachment，loneliness，separation，seclusion； “singleness” （of heart），discrimination （of thought） PTS
विवेक viveka [act. vivic]
True knowledge , discretion , right judgement , the faculty of distinguishing and classifying things according to their real properties ChUp.
विविच् vivic [ vi-√ vic ]
- divide asunder , separate from ŚBr.
- to shake through (acc.) RV.
- to distinguish , discern , discriminate KaṭhUp. (contemporary)
- to go asunder , separate AV.
√ विच् vic [linked to vij]
- to sift , separate (esp. grain from chaff by winnowing) RV. AV.
- to discriminate , discern , judge RV. AV.
√ विज् vij
- to move with a quick darting motion , speed , heave (said of waves) ŚBr.
- to start back , recoil , flee from RV. AV.
- to tremble at, start or flee from RV.
- to speed , accelerate PañcavBr.
Compare with Paṭisallāna
“And how, Nandiya, is a noble disciple one who dwells diligently?
Here, Nandiya, a noble disciple possesses confirmed confidence in the Buddha thus: ‘The Blessed One is … teacher of Devas and humans, the Enlightened One, the Blessed One.’ Not content with that confirmed confidence in the Buddha, he makes further effort for solitude by day and for seclusion at night.
Kathañca, nandiya, ariyasāvako appamādavihārī hoti?
Idha, nandiya, ariyasāvako buddhe aveccappasādena samannāgato hoti—itipi so bhagavā … pe … satthā devamanussānaṃ buddho bhagavāti. So tena buddhe aveccappasādena asantuṭṭho uttari vāyamati [vi+ā+yam] divā pavivekāya rattiṃ paṭisallānāya.
Paṭisallāna - [paṭi+saṁ+ lī]
प्रतिसंलयन pratisaṃlayana [ prati-saṃ-layana ] - √ lī
- against , in opposition to.
संलयन saṃlayana [ saṃ-layana ]
लयन layana [ act. √ lī ]
√ ली lī
- to cause to cling Br.
VEDA - UPANIṢAD
‘As, dear boy, the bees make honey by collecting juices from different trees and reduce them into one essence, and there, as these juices have no such discrimination as “I am the juice of this tree, I am the juice of that tree”; even so, dear boy, all these creatures having merged into Being, do not know, “We have merged into Being.”
yathā somya madhu madhukṛto nistiṣṭhanti nānātyayānāṃ vṛkṣāṇāmrasānsamavahāramekatāmrasaṃ gamayanti ॥ 6.9.1॥
te yathā tatra na vivekaṃ labhante 'muṣyāhaṃ vṛkṣasya raso'smyamuṣyāhaṃ vṛkṣasya raso'smītyevameva khalu somyemāḥ sarvāḥ prajāḥ sati saṃpadya na viduḥ sati saṃpadyāmaha iti ॥ 6.9.2 ॥
Thus have I heard. On one occasion a certain bhikkhu was dwelling among the Kosalans in a certain woodland thicket. Now on that occasion, while that bhikkhu had gone for his day’s abiding, he kept on thinking evil unwholesome thoughts connected with the household life.
Then the devatā that inhabited that woodland thicket, having compassion for that bhikkhu, desiring his good, desiring to stir up a sense of urgency in him, approached him and addressed him in verses:
“Desiring seclusion you entered the woods,
Yet your mind gushes outwardly.
Remove, man, the desire for people;
Then you’ll be happy, devoid of lust.
“You must abandon discontent, be mindful—
Let us remind [you] of that [way] of the good.
Hard to cross, indeed, is the dusty abyss;
Don’t let sensual dust drag you down.
“Just as a bird littered with soil
With a shake flicks off the sticky dust,
So a bhikkhu, strenuous and mindful,
With a shake flicks off the sticky dust.”
Then that bhikkhu, stirred up by that devatā, acquired a sense of urgency.
evaṃ me sutaṃ — ekaṃ samayaṃ aññataro bhikkhu kosalesu viharati aññatarasmiṃ vanasaṇḍe. tena kho pana samayena so bhikkhu divāvihāragato pāpake akusale vitakke vitakketi gehanissite. atha kho yā tasmiṃ vanasaṇḍe adhivatthā devatā tassa bhikkhuno anukampikā atthakāmā taṃ bhikkhuṃ saṃvejetukāmā yena so bhikkhu tenupasaṅkami; upasaṅkamitvā taṃ bhikkhuṃ gāthāhi ajjhabhāsi —
“vivekakāmosi vanaṃ paviṭṭho,
atha te mano niccharatī bahiddhā.
jano janasmiṃ vinayassu chandaṃ,
tato sukhī hohisi vītarāgo.
“aratiṃ pajahāsi sato, bhavāsi sataṃ taṃ sārayāmase.
pātālarajo hi duttaro, mā taṃ kāmarajo avāhari.
“sakuṇo yathā paṃsukunthito, vidhunaṃ pātayati sitaṃ rajaṃ.
evaṃ bhikkhu padhānavā satimā, vidhunaṃ pātayati sitaṃ rajan”ti.
atha kho so bhikkhu tāya devatāya saṃvejito saṃvegamāpādīti.
Take notice how the Chandogya Upanishad and the Pali Sutta are conveying an opposite notion. The former asks for no separation, while the latter does ask for the contrary. The core of the Upaniṣadic vs. Buddhistic philosophies.