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.

Bhagavad Gita Verse 21, Chapter 10

aadityaanaamaham vishnurjyotishaam raviranshumaan |
mareechirmarutaamasmi nakshatraanaamaham shashee || 21 ||
 
Among the Aadityaas I am Vishnu, among the bright objects I am the radiant sun, among the Marutas I am Mareechi, among the stars I am the moon.
 
aadityaanaam : among the Aaadityaas
aham : I
vishnuhu : Vishnu
jyotishaam : among the bright objects
ravihi : sun
anshumaan : radiant
mareechihi : Mareechi
marutaam : among the Marutas
asmi : am
nakshatraanaam : among the stars
aham : I
shashee : moon
 
Shri Krishna begins enumerating Ishvara’s expressions in this shloka. He begins by saying that among the Aadityaas or the sons of Aditi, he is Vishnu. The twelve sons of Aditi were Dhaataa, Mitra, Aryamaa, Rudra, Varuna, Soorya, Bhaga, Vivasvaan, Poosha, Savitaa, Tvashtaa and Vishnu. Vishnu also refers to the Vaamana avatar.
 
Next, Shri Krishna says that Ishvara is “Ravi”, the sun, among all the bright objects in the universe. He uses the word “anshumaan” meaning radiant to describe the sun. So whenever we see the brilliance of the sun, our mind should immediately go towards the might of Ishvara that is shining through the sun. And just like Ishvara’s luminosity is present in the sun during the day, it is present in the moon during the night.
 
There is an episode in the Sunder Kand of the Tulsi Ramayana where Lord Hanumaan was captured bound with ropes in Lanka. It is said that there are forty nine types of wind deities known as Marutas. Hanumaan was the son of the lord of wind, Vayu. When all forty nine types of winds began to blow, he untied himself of all the ropes and flew from building to building, burning each one with his flaming tail. Shri Krishna says that Mareechi, the prominent among the Marutas, is Ishvara’s expression.
 
With these expressions in our mind, we will never be disconnected from Ishvara. In the day, we can look at the sun - it is Ishvara. When the winds blow, it is Ishvara. In the night, the moon is Ishvara.