Just as the one sun lights up this whole world, so the owner of the field lights up the entire field, O Bharata.
Explanation
Krishna continues describing how the knower of the field (kṣetrajña, the self), here called the field's owner (kṣetrī), relates to the body, the "field" (kṣetra). Having said the self is untouched like space, he now gives the image of the sun: one sun illuminates the whole world without being changed by it, just as the self makes the whole body and mind known through awareness. Traditions differ on whether this self is one universal consciousness (Advaita) or each individual self is distinct yet dependent on God (Vishishtadvaita and Dvaita).