sukhamātyantikaṃ yattad buddhigrāhyamatīndriyam |
vetti yatra na caivāyaṃ sthitaścalati tattvataḥ ||6.21||
...(and when) one recognises this absolute happiness, which is known by the intellect, which is beyond sense perception and when, being rooted (therein) one never moves away from the truth of oneself.
3)ātyantikaṃ sukham - absolute happiness is there only when there is no limitation in any condition. Any form of happiness which is conditioned by any object or situation is limited only. If I am in contact with the object of happiness (including the thought of that particular object), then I am happy. This kind of happiness comes and goes, because object/set-up/thought can't be there always. Even if one said that external object/situation is always available for oneself, but this person may not in the mood for it. Happiness which is born of an external condition depends upon two situations, the external condition itself and a conducive internal mental condition. Only when one owns up the true nature of oneself which is limitless, one recognises the unconditioned happiness. This absolute happiness is recognised by intellect - buddhigrāhyam, but beyond sense perception - atīndriyam. This is a very good explanation for us to understand further that absolute happiness is not experiential, but is to be understood and own up as the knowledge of the self, which is not anything other than me.
When this recognition of one's true nature takes place, it will not go away - 4)sthitah na calati tattvataḥ. How one will not deviate from the knowledge of one's true self, compare to the possibility of forgetting any knowledge other than myself? What is the difference between knowing myself - ātmā and anything other than myself - anātmā?
To recognise an object, lets say a pot, our mind must assume the very form of the pot, called pot-thought. This is the first step. Then second operation is the recognition of that pot-thought, thereby recognising the pot. One is the objectification of the object, by thought, and the other is the recognition of the thought. The objectifying thought is recognised by another thought, which is the seer-thought. I who identified with the seer (I-thought) recognises the pot-thought. Therefore I can say "this is a pot". Any piece of knowledge has its peculiar connection, ātma-anātma sambandha - connection between the self as the knower and the object that is objectified by that knower. It takes place by these two step operations. However in the case of recognising my true nature, there is only one step operation. For recognition of ātma also, there must be a thought. This thought is introduced by śāstra and brought back by the contemplator in nididhyāsana. There is thought that objectifies ātma as me, that assumes the very form of ātma which is sat-cit-ānanda which is me alone. Because I am none other than sat-cit-ānanda ātma, therefore there is no second operation which is recognition of that thought. The knower and the known are one and the same, therefore there is only one step operation which is objectifying-thought which destroys the ignorance about the self.
Therefore when this recognition of one's true nature takes place, it will not go away - 4)sthitah na calati tattvataḥ, unlike the pot-thought comes and goes, thus it is said as beyond perception - atīndriyam. This absolute happiness is recognised by intellect as "I". When it is rooted, it will never go away.
yaṃ labdhvā cāparaṃ lābhaṃ manyate nādhikaṃ tataḥ |
yasmin sthito na duḥkhena guruṇāpi vicālyate ||6.22||
...and, having gained which, one does not think there is any other better gain than that, established in which, one is not affected even by a great sorrow...
5)yaṃ labdhvā cāparaṃ lābhaṃ manyate nādhikaṃ tataḥ - having owned up the nature of the self, one doesn't consider any other gain is greater. Because self-knowledge is that by knowing which everything is as well known. Just like in the world of golden ornament, when gold is known as the basis, all the golden ornament is as well known. When everything is known, nothing there is available to compare with. This is a limitless gain. And this limitless is not other than myself. The seeker and the sought are one and the same. When one established in which, one is not affected even by a great sorrow - 6)duḥkhena guruṇāpi na vicālyate.