Just as the one sun illumines the whole world, so also the Lord of the field (Supreme Self)
illumines the whole field, O Arjuna.
In simple words
Krishna gives another image: "Just as one single sun lights up the entire world, the Lord of the field — the one supreme self — lights up every field, every body, everywhere."
Word-by-word meanings
यथाasप्रकाशयतिilluminesएकःoneकृत्स्नम्the wholeलोकम्worldइमम्thisरविःsunक्षेत्रम्the fieldक्षेत्रीthe Lord of the field (Paramatma)तथाsoकृत्स्नम्the wholeप्रकाशयतिilluminesभारतO descendant of Bharata (Arjuna)
13.34 यथा as? प्रकाशयति illumines? एकः one? कृत्स्नम् the whole? लोकम् world? इमम् this? रविः sun? क्षेत्रम् the field? क्षेत्री the Lord of the field (Paramatma)? तथा so? कृत्स्नम् the whole? प्रकाशयति illumines? भारत O descendant of Bharata (Arjuna).Commentary The Supreme Self is one. It illumines the whole matter from the Unmanifested down to the blade of grass or a lump of clay? from the great elements down to firmness or fortitude. (Cf. verses 5 and 6.) Just as the sun is one? just as the sun illumines the whole world? just as the sun is not tainted? so also the Self is One in all bodies? It illumines all the bodies and It is not contaminated.
Contemporary scholarly and practical interpretations for modern seekers.
This interpretation draws on a specific tradition and may not represent the view of any single school. For authoritative guidance within a specific tradition, seek a qualified teacher.
Modern
In the spiritual literature, this illustration given by the Lord, the Charioteer of Arjuna, is most illuminating. This illustration makes comprehensible the relationship between the field and the knower of the field. Just as the one sun stationed in the distant sky perpetually illuminates this entire world, so too does the one atman merely illuminate all objects, bodies, minds, and intellects. Though in common parlance we say the sun illuminates the world, and thus we attribute the agency of illumination to the sun, yet upon reflection it becomes clear that such attribution is entirely without foundation. Action is that which begins at one moment and ends at another, and is generally performed for the accomplishment of some definite purpose or intention. From this perspective, the sun does not illuminate the world. Rather, illumination is its very nature, and all things become manifest in its presence. Similarly, consciousness is the very essence of the atman, and all things become known in its presence.
The sun illuminates all things in this world—the auspicious and inauspicious, the virtuous and the wicked, the beautiful and the ugly—yet it remains untainted by the qualities or defects of any of them. In the same way, the atman—which is existence, consciousness, and bliss—though it expresses itself through the limiting adjuncts of mind, intellect, and body, remains entirely unaffected by the sins of the mind, the distortions of the intellect, and the transgressions of the body.
Concluding the discussion of the field and the knower of the field that has been examined in this chapter, the Lord speaks thus: