क्षेत्रक्षेत्रज्ञयोरेवमन्तरं ज्ञानचक्षुषा।भूतप्रकृतिमोक्षं च ये विदुर्यान्ति ते परम्॥
kṣetra-kṣetrajñayor evam antaraṃ jñāna-cakṣuṣābhūta-prakṛti-mokṣaṃ ca ye vidur yānti te param
Word by word
The verse says
Those who know, with the eye of knowledge, the difference between the field and the one who knows the field, and the freeing of beings from nature — they reach the highest.
In plain words
Jñāna-cakṣuṣā — with the eye of knowledge.
Not with reasoning, though the chapter has done plenty. An eye. Something you see with.
The chapter that began by asking for definitions ends by describing a way of looking.
Where you've felt this · in growing older
Your grandmother can tell from across the room that something is wrong with you, before you have said anything, and she is right. She is not deducing it. Forty years of looking at people has produced an eye, and the eye does the work before the thinking starts.
Going deeper
Ending on an eye rather than an argument tells you what the preceding thirty-four verses were for.
The chapter gave an inventory, twenty qualities, a set of paradoxes and a careful division of labour between nature and person. None of that was the destination. What it was building toward is a way of seeing in which the distinction between the field and its knower is simply apparent, the way a trained eye sees a thing an untrained one looks straight past.
Chapter 11 made the same point from the other direction, when Arjuna had to be given an eye before he could see anything at all.
So the honest measure of whether this chapter has worked is not whether you can define kṣetra. It is whether, the next time a mood arrives, something in you registers it as weather in a field rather than as news about who you are.