Bhagavad Gita Verse 33, Chapter 13

yathaa prakaashayatyekaha kritsnam lokamimam ravihi |
kshetram kshetree tathaa kritsnam prakaashayati bhaarata || 33 ||
 
Just as the one sun illumines the entire world, so does the knower of the field illumine the entire field, O Bhaarata.
 
yathaa : just as
prakaashayati : illumines
ekaha : the one
kritsnam : entire
lokam : world
imam : this
ravihi : sun
kshetram : field
kshetree : knower of the field
tathaa : so does
kritsnam : entire
prakaashayati : illumines
bhaarata : O Bhaarata
 
The example of space in the previous shloka was meant to illustrate the unaffected and untainted nature of the self. In this shloka, the example of the sun is given to highlight the actionless nature of the self. The sun is located millions of miles away from the earth, yet it enables life on earth to exist. Minerals, plants, animals and humans, everything and every being survives only from the sun’s energy. But the sun never acts. All of the actions happen on our planet distinct and separate from the sun.
 
Shri Krishna says that the self in us, the "I" in us is similar in nature to the sun. The self or the knower of the field, the kshetrajnya, illumines or knows the actions taking place in the kshetra, the field, our body, which is a part of Prakriti. Furthermore, the self does not take on the notion of pride or doership in the actions of the body, neither does it get differentiated due to the differences or modifications of Prakriti, just like the sun never claims doership nor gets differentiated due to the variety of form on our planet.
 
So, if the self is the sole knower of all of the actions in our body, how does our intellect know things? With respect to the analogy of the sun, the intellect can be compared to a pool of water that reflects the light of the sun. The intellect is just an instrument that functions due to tje knowledge of the self. If the intellect is calm and steady, it works perfectly in interpreting the information sent to it from the mind and senses. If it is agitated or dull, it cannot work perfectly, just like the sun’s reflection is disturbed when the pool of water is agitated or muddy.
 
Here, Shri Krishna asserts that the self is of the nature of "chit". It is knowledge, awareness, consciousness personified.