न जायते म्रियते वा कदाचिन्नायं भूत्वा भविता वा न भूयः।
अजो नित्यः शाश्वतोऽयं पुराणो न हन्यते हन्यमाने शरीरे।।2.20।।
Never is this One born, and never does It die; nor is it that having come to exist, It will again cease to be. This One is birthless, eternal, undecaying, ancient; It is not killed when the body is killed.
But how is this atman changeless? [from the previous shloka]
This atman is neither born nor does it die. And this holds good for all point of time. What is the meaning of birth? That which having been non-existent, comes into being, is said to be born. And that which having been, ceases to be, is said to die. This atman is unlike both. Therefore, it is said to neither die nor be born. Since it does not die, it is eternal. Since it is never born, it is called unborn. Thus, the atman is both unborn and eternal. It also exists for ever. There is no decay in it because it is partless. And being devoid of any gunas, there is no decay to atman due to decay of gunas either. That is why word shaswat is used for it. So, is there any growth in it? No. And to show that, the word puranah (ancient) is used. However, being partless, this atman, was new even in the past. Even as the body is slain, the atman is not slain.
The thrust of the shloka is that the atman is devoid of six modifications which the empirical objects are affected by.
It was explained in the previous shloka that atman is neither the subject nor the object of the action of killing. In the present verse, Bhagvan establishes the reasons for its freedom from transformation. And now he concludes the argument in next shloka.