अविनाशि तु तद्विद्धि येन सर्वमिदं ततम्।
विनाशमव्ययस्यास्य न कश्िचत् कर्तुमर्हति।।2.17।।
But know That to be indestructible by which all this is pervaded. None can bring about the destruction of this Immutable.
Now what is it which is eternally existent?
You should know that as the indestructible which never perishes. That is Sat. That is Brahman. This entire world is pervaded by Brahman just as the pots etc are pervaded by space.
What is the meaning of destruction? It means non-perception or non-being. What is the meaning of changeless? It is that which neither increases nor decreases. Now this Brahman, called by the word Sat, is partless and hence there is never any change in its own nature. That is so unlike the body etc. Further, there is no change in its properties too, because it does not have any properties. One is said to change (decay) if there is change is one’s properties, wealth etc. Not so in the case of Brahman.
This Brahman is actually the atman. This Brahman can never be destroyed. Not even God can destroy this atman because atman is Brahman and it is contradictory to have any activity in itself.
Now what is that ‘asat’ which changes from its own existence? [in next shloka]