kshetragnya chaapi maam viddhi sarvakshetreshu bhaarata |
kshetrakshetragnayorjnyaanam yattajgnyaanam matam mama || 2 ||

And also, understand that I am the knower of all fields, O Bhaarata. That knowledge which pertains to the field and its knower, in my opinion, that is (real) knowledge.
kshetragnya : knower of the field
cha : and
api : also
maam : I
viddhi : understand
sarvakshetreshu : all fields
bhaarata : O Bhaarata
kshetrakshetragnayoho : field and its knower
jnyaanam : knowledge
yat : that which
tat : that
jnyaanam : knowledge
matam : opinion
mama : my
Shri Krishna began the previous chapter by defining two terms: kshetra which means field, and kshetragnya which means the knower of the field, one who knows himself as distinct from the field. In this shloka, Shri Krishna uses these terms to indicate the identity or oneness of the kshetragnya in all kshetras. Let us try to understand this very important point. Like Arjuna did in the first chapter, most of us consider our self, our “I”, as this body, and therefore get stuck in the sorrows of this world. As we understand the message of the first six chapters, we understand that we are the eternal essence which is different than our body. We then understand from the next six chapters that Ishvara is the foundation of this world as the lower Prakriti or matter, and higher Prakriti or consciousness. Now, in this shloka, Shri Krishna says that there is no such distinction between the individual eternal essence and the foundation of this world. There is only one kshetragnya, and any notion of separation is illusory, caused by avidyaa or ignorance. This is the great statement, the mahaa vaakya “Tat Tvam Asi” of the Vedas. You and Ishvara are the same in essence, there is no difference.
When we first hear someone say that we are the same as Ishvara, we don’t find it quite logical. We say, how can a body that is five feet eight inches tall be the same as Ishvara who is large enough to contain all the planets and stars of the universe within him? To answer this, we have to first remember that “Tat Tvam Asi” is not meant to be taken literally. Again, let us proceed step by step. First, let us understand the term “upaadhi”. It means something that limits or conditions a more general thing. A wave is an upaadhi of water. A light bulb is an upaadhi of electricity. An ornament is an upaadhi of gold. We can obtain the general thing that the upaadhi limits or hides by a process of mental removal. Mentally remove the wave, and you get water. Mentally remove the bulb, you get electricity. Mentally remove the ornament, you get gold. We can take this even further. Mentally remove the labels Mercedes Benz and Maruti 800 from the word car, and you get metal, rubber, petrol and plastic. Mentally remove the labels Indian and American from the word person, and you get flesh, bones and blood.
Now, having undersood what an upaadhi is, and how it can be mentally removed, let us proceed to understand what the word “Asi” in “Tat Tvam Asi” indicates. It is not to be literally interpreted as Tvam (You) Asi (are equal to) Tat (Ishvara). Asi means “are equal to, when you remove the upaadhi”. If we apply this meaning, the mahaa vaakya reads : Tvam (You) Asi (are equal to) Tat (Ishvara) when you remove both the upaadhis of You and Ishvara. I as a human have the upaadhi of the physical body and everything it contains. Ishvara has the upaadhi of the entire universe in its visible form including all the trees, plants, animals, people, stars, planets etc that we see with our senses. If we mentally remove our body as an upaadhi, and we also mentally remove the visible universe as an upaadhi, we are left with the same eternal essence in both cases. That same eternal essence, that same kshetragnya, is present in all kshetras, which are the same as upaadhis.
Another meaning of the word “upaadhi” is title or qualification, which can help us understand this shloka in a different way. Let’s say there are two brothers in a house. One of them has a PhD in physics, and the other is a manager in a multinational. When each of them is in their respective offices, they use their titles as part of their job responsibilities. But when they perform a pooja or a holy ritual, lets say, they mentally remove their upaadhis or titles. If they did not remove their titles, their conversation would go like this: “Hey PhD in physics, do this. Hey manager, pour the clarified butter”. They would never see that they are really the same family under the titles that seemingly create differences. This means that removing upaadhis to realize our oneness with Ishvara can be difficult, but it is not impossible. We know how to remove small upaadhis. Shri Krishna will teach us how to remove the biggest upaadhis in this chapter through practical techniques. He says that ultimately, knowledge of the kshetragnya, the kshetras or upaadhis, and how to realize oneness under the kshetras, is the ultimate knowledge that one has to learn, and not any other type of knowledge.