To elev rote further this body in sanskrit is called shatra[field].and the ruler of body is called shatrg [knower of the field].meaning the guide and inspirer of deeds[karma].this as been defined and explained by wise[knower].though this chapter lord krishana defined the realization be tween physical body and the spiritual truth.
this body is field because we sow the seed of karma[deeds] likewise a field and harvest crops of our bad and good actions[karma].my master sant nikka singh ji always used to say that unity of knower and known never happens. known being a part of nature is always visible in all its actions where as the knower is constant.the physical existence of nature is a part of known.as water and oil never meets.this expression of our being only physical related to nature to nature and nothing beyond.our feelings of good and bad happens are simply imposed, artificially on reality.this is called tadatma in vadanta.The elementary truth as has been explained by this solaka.