In plain words
It is never born, nor does it ever die. Having once been, it never ceases to be. Unborn, eternal, everlasting, ancient—it is not killed when the body is killed.
Word for word
It is not born, nor does it die, at any time; nor [is it that] this, having been, will not be again; unborn, eternal, everlasting, this ancient [one] is not slain when the body is slain.
न जायते म्रियते वा कदाचित्नायं भूत्वा भविता वा न भूयःअजो नित्यः शाश्वतोऽयं पुराणोन हन्यते हन्यमाने शरीरे
Other commentaries
The commentators
▸Bhagavadgītābhāṣyam
कथमविक्रय आत्मेति द्वितीयो मन्त्रः —
न जायते न उत्पद्यते, जनिलक्षणा वस्तुविक्रिया न आत्मनो विद्यते इत्यर्थः । तथा न म्रियते वा । वाशब्दः चार्थे । न म्रियते च इति अन्त्या विनाशलक्षणा विक्रिया प्रतिषिध्यते । कदाचिच्छब्दः सर्वविक्रियाप्रतिषेधैः सम्बध्यते — न कदाचित् जायते, न कदाचित् म्रियते, इत्येवम् । यस्मात् अयम् आत्मा भूत्वा भवनक्रियामनुभूय पश्चात् अभविता अभावं गन्ता न भूयः पुनः, तस्मात् न म्रियते । योहि भूत्वा न भविता स म्रियत इत्युच्यते लोके । वाशब्दात् नशब्दाच्च अयमात्मा अभूत्वा वा भविता देहवत् न भूयः । तस्मात् न जायते । यो हि अभूत्वा भविता स जायत इत्युच्यते । नैवमात्मा । अतो न जायते । यस्मादेवं तस्मात् अजः, यस्मात् न म्रियते तस्मात् नित्यश्च । यद्यपि आद्यन्तयोर्विक्रिययोः प्रतिषेधे सर्वा विक्रियाः प्रतिषिद्धा भवन्ति, तथापि मध्यभाविनीनां विक्रियाणां स्वशब्दैरेव प्रतिषेधः कर्तव्यः अनुक्तानामपि यौवनादिसमस्तविक्रियाणां प्रतिषेधो यथा स्यात् इत्याह — शाश्वत इत्यादिना । शाश्वत इति अपक्षयलक्षणा विक्रिया प्रतिषिध्यते । शश्वद्भवः शाश्वतः । न अपक्षीयते स्वरूपेण, निरवयवत्वात् । नापि गुणक्षयेण अपक्षयः, निर्गुणत्वात् । अपक्षयविपरीतापि वृद्धिलक्षणा विक्रिया प्रतिषिध्यते — पुराण इति । यो हि अवयवागमेन उपचीयते स वर्धते अभिनव इति च उच्यते । अयं तु आत्मा निरवयवत्वात् पुरापि नव एवेति पुराणः ; न वर्धते इत्यर्थः । तथा न हन्यते । हन्ति ; अत्र विपरिणामार्थे द्रष्टव्यः अपुनरुक्ततायै । न विपरिणम्यते इत्यर्थः । हन्यमाने विपरिणम्यमानेऽपि शरीरे । अस्मिन् मन्त्रे षड् भावविकारा लौकिकवस्तुविक्रिया आत्मनि प्रतिषिध्यन्ते । सर्वप्रकारविक्रियारहित आत्मा इति वाक्यार्थः । यस्मादेवं तस्मात् ‘उभौ तौ न विजानीतः’ इति पूर्वेण मन्त्रेण अस्य सम्बन्धः ॥ २० ॥
In plain words
"But how is the Self unchanging?" — the second mantra:
'Unborn' means: nothing ever arises here that wasn't already there. The kind of change that happens when a thing comes into existence simply doesn't touch the Self. In the same way, it doesn't die. ('Or' here just means 'and.') Once you've said it's never born and never dies, you've ruled out change at both ends of a life -- and the word 'ever' locks that shut for all time: not born, ever; not dying, ever. Why? Because something that has already come into being and will simply never stop being cannot be said to 'die' -- dying, in ordinary language, means a thing that existed will one day not exist. And something that never failed to exist in the first place, and comes into being the way a body does, cannot be said to be 'born' either -- being born, in ordinary language, means a thing that didn't exist starts existing. None of that describes the Self. That's why it's called 'unborn,' and because it never dies, 'eternal.' Now, ruling out the first change and the last -- birth and death -- technically rules out everything in between too. But that's easy to miss, so each of the changes in the middle gets its own word, so nothing -- not aging, not any of it -- slips through unnamed. That's why the verse keeps going: 'eternal' rules out decay. Something is 'eternal' simply because it goes on and on. It can't wear down in its own nature, because it has no parts to wear down, and it can't wear down through losing qualities, because it has no qualities to lose. And the opposite of decay -- growth -- gets ruled out too, by the word 'ancient.' Normally, something grows by gaining parts, and we call that 'fresh.' But the Self, having no parts, is ancient even at its most ancient, and endlessly new -- which is exactly why it's called 'ancient': it simply doesn't grow. In the same way, it isn't 'struck.' Here 'struck' has to mean 'altered,' or we'd just be repeating ourselves -- the point is that it isn't altered even while the body it's associated with is being struck down and altered. This one verse is quietly ruling out all six of the changes anything ordinary goes through -- being born, existing, growing, changing, decaying, dying. The Self has none of them, not one. And that's exactly why it connects back to what was just said: the two people arguing over 'I killed him' and 'I was killed' -- neither of them actually knows the Self at all.
Close to the Sanskrit
"How is the Self unchanging?" — thus; the second mantra:
'Is not born' -- does not arise; the modification characterized by birth, [inherent] in a substance, does not exist for the Self -- such is the meaning. Likewise, nor does it die. The word 'vā' is used in the sense of 'ca' (and). '[Nor] does it die' -- thus the last modification, characterized by destruction, is negated. The word 'kadācit' (ever) is to be connected with all the negations of modification: 'it is never born, it never dies' -- thus. Because this Self, having come to be, having experienced the act of coming-into-being, will not afterward cease to be, will not go to non-existence again -- therefore it does not die. For one who, having existed, will not exist [again], is said in the world to 'die.' From the words 'vā' and 'na', this Self, not having previously not-existed, will not come to be like a body, ever again -- therefore it is not born. For one who, not having existed, comes to be, is said to 'be born.' Not so the Self. Therefore it is not born. Since this is so, therefore [it is] unborn; since it does not die, therefore [it is] eternal as well. Although, by the negation of the first and last modifications, all modifications are [thereby] negated, nevertheless, for the modifications occurring in between, negation must be made by their own separate words, so that the negation of all the unmentioned modifications too -- youth and the rest -- might also hold; with this in view he says 'śāśvata' and so on. 'Śāśvata' (eternal) -- thus the modification characterized by decline is negated. That which perpetually exists is 'śāśvata.' It does not decline in its essential nature, because it has no parts; nor does it decline through the loss of qualities, because it has no qualities. The modification opposite to decline, namely growth, is also negated -- by the word 'purāṇa' (ancient). For one who is augmented by the accession of parts grows, and is [then] called 'renewed.' But this Self, being without parts, is 'ancient' even in the past, ever new -- that is why it is called 'purāṇa'; meaning it does not grow. Similarly, nor is it slain. [The word] 'hanti' here is to be understood in the sense of transformation, to avoid redundancy. Meaning: it is not transformed, even while the body is being slain, being transformed. In this verse, six changes of state -- the ordinary modifications a substance undergoes -- are negated of the Self. 'The Self is devoid of every kind of modification' -- this is the meaning of the sentence. Since this is so, its connection with the previous verse, '[both of] those two do not know,' is thus [established].