Bhagavad Gita Verse 9, Chapter 4

janma karma cha me divyamevam yo vetti tattvataha |
tyaktvaa deham punarjanma naiti maameti sorjuna || 9 ||
 
My birth and action are divine. One who knows this in essence, having given up the body, is not born again; he obtains me, O Arjuna.
 
janma : birth
karma : action
cha : and
me : my
divyam : divine
evam : in this way
yah : one who
vetti : knows
tattvataha : in essence
tyaktvaa : give up
deham : body
punah, janma : rebirth
na : does not
eti : obtain
maam : me
eti : obtain
sah : he
arjuna : O Arjuna
 
In the last two shlokas, Shri Krishna gave the reason for his avataara. Now the question arises: how does this knowledge help the spiritual seeker? He says that once we understand the secret of Ishvaraa's birth and action, we will understand the secret of our action as well.
 
What is the secret of Ishvaraa's birth and action? It looks to us that Ishvaraa is born, and that Ishvaraa performs action. But that is not the case. Through the power of Ishvaraa's Maaya, it only looks like Ishvaraa takes birth and performs action. It is just an illusion. As we have seen earlier, the eternal essence does not perform action, only prakriti - also called maaya - performs action.
 
Now, the jeeva within us is identified with the body, mind and intellect. Its birth is based on past karmaas. It performs karmaas with a sense of doership. In other words, it thinks that it is performing actions. But from the standpoint of the eternal essence, there is no doership or enjoyership. It is prakriti alone that acts. Just like Ishvaraa does not perform action, the jeeva also does not perform action. The jeeva is one with Ishvaraa.
 
So therefore, one who truly and completely understands this point will drop identification with his body, and begin identifying with the eternal essence. That is what is meant by the phrase "deham tvaktvaa": the jeeva has stopped identification of the body.
 
Here, academic knowledge is not enough. We need a first-hand understanding that prakriti performs actions and not the eternal essence. That first-hand understanding can only be gained through meditation, which is explained later in the Gita.
 
A simple way to understand the teaching so far is as follows. The individual jeeva is like a wave in the ocean. Ishvaraa is like the ocean. The eternal essence or brahman is water. Once the wave realizes that it is the same water as Ishvaraa, it is free from the limitations of its tiny form.