Those who, with the power of spiritual insight, know the difference between the Field (kshetra) and the Knower of the Field (Kshetrajña), and equally the truth about the freedom from the stronghold of Prakṛti, reach the Supreme.
Though Arjuna enquired about six items in the beginning of the chapter, and Krishna also explained them, in conclusion Krishna points only to the concepts of kshetra and Kshetrajna. Knowing the kshetra is rather easy, but to know the Kshetrajna is not so. If the kshetra is the object, Kshetrajna is the Subject. If kshetra is transforming, changeful, ever and ever, the Kshetrajna, the Self, is absolutely changeless, imperishable. In fact, the only changeless existence we can think of is the Kshetrajna, the Self.
The only place where one can search for and find the Kshetrajna, is within one’s own body. This is what everyone denotes by the term ‘I’, not knowing its real dimension. It is experiential to all. But, a full understanding of its difference from the kshetra, is to be realized by discrimination, contemplation and Self-absorption.