Śaṅkara’s doctrine of liberation in the Gītā is set out briefly in his introduction: the Highest good … is from the Course (dharma) of Estab- lishment-in-Knowledge-of-Self (ātma-jñāna-niṣṭhā), preceded by completely casting off all action (sarva-karma-saṃnyāsa). He presents it at length at the end, in the commentary to XVIII.50, 54, and 55, in the following extracts.
That supreme establishment-in-Knowledge (niṣṭhā jñānasya yā parā niṣṭhā) is its final resting-place (pary-avasāna), its culmination (pari-samāpti)
That is the supreme culmination of Knowledge of Brahman (brahma-jñānasya yā parā parisamāpti).
XVIII. 54 (extract)
Such a man of jñāna-niṣṭhā (establishment-in-Knowledge), My devotee (bhakta) worshipping Me the supreme Lord, has attained the fourth, the highest, devotion (bhakti), that which has Knowledge. As it was said
(VII.18) The fourth class (the class of Knowers) worship Me. So by that bhakti of Knowledge –
XVIII. 55 (extract)
By devotion he knows Me, how great and who I am in truth:
Then having known Me in truth, he thereupon enters.
(Śaṅkara) Then having known Me in truth, he thereupon enters into Me. It is not meant by this that there are two separate actions – an entering apart from Knowledge. Having known, he thereupon enters means Knowledge alone with no further result. So it was said: Know me as the Knower of the field (XIII.2).
(Opponent) It is a contradiction to what was said previously (XVIII.50) that what is highest is Establishment (niṣṭhā) of Knowledge, and by that he knows Me. To explain the contradiction: when the Knowledge of something simply arises in a Knower, then the Knower is said to know that thing. He does not look to some establishment, some going over again, of the knowledge. So the contradiction is, that it was said previously that it is not by knowledge but by Establishment-of-Knowledge (jñāna-niṣṭhā), by going over it again that one knows.
(Answer) There is no contradiction, for the force of the word Establishment (niṣṭhā) is, the definite coming-to-rest (avasānatva) in Self-being (ātma-anubhava) of a Knowledge that has met the conditions for its own rise (utpatti) and maturing (paripāka), (namely) absence of obstacles. That is its Establishment (niṣṭhā).
The concomitant conditions for the rise (utpatti) and maturing (paripāka) of the Knowledge from scripture and instruction of a teacher are: purity of buddhi and so on, the (twenty) qualities beginning with humility (XIII.7–11). When from them arises the Knowledge that the Field-Knower (kṣetra-jña) and the highest Self (paramātman) are one, and there is also renunciation of all actions tied up with notions of differences of agent, instruments and so on – when there is thus definite being-the-Self (svātma-anubhava) – that state is what is meant by the highest Establishment-of-Knowledge (jñāna-niṣṭhā).
As against the other three types of devotion (bhakti) given in VII. 16, namely of those in danger, those seeking Knowledge, or those seeking success in the world, this jñāna-niṣṭhā is called the fourth kind of devotion, the highest. By that highest devotion he knows the Lord in truth. Thereupon, the idea (buddhi) of any difference between the Lord and the Knower of the field, completely ceases. So what is being said is: ‘he knows Me in truth by the devotion (bhakti) which is Establishment-in-Knowledge (jñāna-niṣṭhā), and there is no contradiction.
(There follow citations of texts showing that giving up all sense of ‘I do’ must come before and along with jñāna-niṣṭhā.)
jñāna-niṣṭhā is unremitting persistence (abhiniveṣa) in the idea- stream of the Self Apart. Bhakti-yoga of serving the Lord by one’s proper action has for its perfection this result: becoming capable of jñāna-niṣṭhā. Thus the yoga of bhakti brings about jñāna-niṣṭhā, which has mokṣa as its final resting-place (avasāna). The Lord goes on to praise that yoga in verse 56.
In this short summarizing passage, XVIII.55, Śaṅkara twice distinguishes between the rise (utpatti) of Knowledge and its mature (paripãka) state. Elsewhere he similarly distinguishes Right Vision when it has just arisen (utpanna-samyag-darśana) from its established state (samyag-darśana- niṣṭhā).
The notion of maturing (paripāka) involves time, though not a fixed time. Another key word in the passage is avasāna, which has the sense of a final goal or stage. There is an association with unharnessing horses, or a river finding its bourn in the ocean. He twice refers to the final goal (avasāna) of Knowledge as anubhava. (A separate note on these terms follows.)
As he says in his commentary to V.12, the final stages are (1) sattva-śuddhi (purity of essence), (2) jñāna-prāpti (obtaining Knowledge), (3) saṃnyāsa giving up ‘I do’ (V.8, and V.13 which is often cited by Śaṅkara in the Gītā commentary on giving up action), (4) jñāna-niṣṭhā, and (5) mokṣa. He calls the whole process krama, meaning a step-by-step progress.
The process of jñāna-niṣṭhā is in fact jñāna-yoga, beginning with Knowledge: it is outlined briefly in XVIII 50–55. Exceptions to the rule of physical renunciation are allowed to ksatriya Knowers (kṣaṭriyāḥ vidvāṃsāḥ) and others. They are listed in the section called Exceptions.
Jñāna-niṣṭhā is described in the Gītā itself in several places. Śaṅkara gives as main ones:
It is also described shortly in many places. It is concerned not with reinforcing Knowledge, which needs no reinforcement, but with removing obstructions. Such normally arise from prārabdha karma. The instruction to jñāna-niṣṭhā would correspond to an instruction to keep a flowing stream clear, as distinct from creating, or reinforcing, the stream. It is removing any branches that might fall into it, but not pushing the water along, or pouring more in. Normally, some disturbances from prārabdha are to be expected, but there might be none. In some places Śaṅkara gives the brief statement: ‘jñāna is the means to mokṣa.’ For instance there should be no prārabdha left at the hour of death: it will have come to an end. Knowledge attained at that time has its fruit instantly: it will have no need to ‘mature’. So the final hour (as the Gītā and Śaṅkara mention) is specifically favourable.