सत्-असत्

Verse 2.16 gives the Gita a test: for the unreal there is no being, and for the real there is no ceasing. Those who see the truth have seen the conclusion about both in just this way.

In plain words, what is always changing cannot carry the permanent stamp "is", and what never changes cannot be made to "not be". In the next verse, 2.17, the real is pointed to: know that by which all this is pervaded to be imperishable.

In life the test works through a simple question: will what I rest on always be as it is? A post, health, a person's presence, every answer is "no". This is not a discouraging discovery; it opens the next question, which is who knows the change.

The Gita does not call the unreal worthless. It only teaches that what by nature changes should not be made our final foundation.