नासतो विद्यते भावो नाभावो विद्यते सतः।उभयोरपि दृष्टोऽन्तस्त्वनयोस्तत्त्वदर्शिभिः॥
nāsato vidyate bhāvo nābhāvo vidyate sataḥubhayorapi dṛṣṭo ’nta stvanayos tattva-darśibhiḥ
Word by word
The verse says
What is not, never comes to be. What is, never stops being. Those who see what is actually there have seen where the line falls between them.
In plain words
The densest verse so far, and the whole argument rests on it.
Two categories. Things that are not really there never actually come into existence. Things that are really there never go out.
And the line between them has been seen — not worked out, not argued. Seen, by people who looked.
Where you've felt this · in creative work
A shadow on a wall is genuinely there in one sense and has no substance of its own in another. Nothing about it is a trick. It simply borrows everything it has from something else, and when that moves, so does it.
Going deeper
Sat and asat — what is, and what is not — are among the oldest terms in Indian thought, and the Gita is using them in a specific way.
Sat here does not mean true as opposed to false. It means what does not depend on anything else to be what it is. Asat is not fake. It is what has no standing of its own.
So the verse is not saying your body is an illusion. It is saying your body is not the kind of thing that can be what you are, because it is continuously borrowed — food, air, time, all of it passing through and none of it staying.
The last phrase is the one that keeps this from being mere theory. Tattva-darśibhiḥ — by those who see things as they are. Seers, not reasoners. The Gita consistently presents this as a matter of perception rather than proof.
That is a real claim and worth holding lightly if you do not share it. What the text offers is not an argument you are supposed to be defeated by, but a report from people who say they looked.