Bhagavad Gita Verse 23, Chapter 13

ya evam vetti purusham prakritim cha gunaih saha |
sarvathaa vartamaanopi na sa bhooyobhijaayate || 23 ||
 
He who thus knows Purusha and Prakriti, along with the gunaas, no matter what his conduct, is never born again.
 
yaha : he who
evam : thus
vetti : knows
purusham : Purusha
prakritim : Prakriti
cha : and
gunaih : gunaas
saha : along with
sarvathaa : whatever
vartamaanaha : conduct
api : no matter
na : not
saha : he
bhooyaha : again
abhijaayate : born
 
To better understand this shloka, let us quickly take a look at the theory of karma. It says that each of us comes with three types of karmas, which are unfulfilled desires that become seeds of future actions. Total karmas or “sanchita” karmas are the entire stock of our karmas. Present life karmas or “prarabdha” karmas are those karmas that are activated in our present life. Expected karmas or “agaami” karmas are those karmas that will be generated due to the results of actions in the present life. These karmas get added to our sanchita karmas, our stock of karmas.
 
As an illustration, consider this. The arrows in an archer’s quiver are sanchita karmas, the arrows that have left his bow are prarabdha karmas, and the arrows that are loaded on the bow are agaami karmas. The Vedas assert that so long as an individual maintains a stock of karmas, he has to take on a body to exhaust those karmas. In each birth, a portion of the stock of karmas is allocated to the individual so that he can exhaust them. By generating further selfish desires, the individual adds to his stock of karmas, and the cycle of birth goes on indefinitely.
 
Shri Krishna says that the one who has properly understood the relationship between Purusha and Prakriti, one who has understood the identification of the eternal essence with Prakriti due to ignorance and the consequent rushing after the gunaas, is never born again. This means that his stock of karmas is destroyed, just like a spark of fire destroys dry hay. He does not generate any further selfish desires, because he is no longer fascinated by the play of the three gunaas. Why does this happen? When one realizes that selfish desire is created by ignorance of one's true nature, it wipes out any notion of selfishness completely. There is no longer an urge to come into contact with Prakriti.
 
Now, this person still has to deal with his prarabdha. His present life karmas continue to be active until his body drops off, after which he does not have to take any further births. The word “api” in the shloka indicates that the individual can continue to perform his duties even if he has realized his true nature as the eternal essence, just like king Janaka continued to rule his kingdom even though he had achieved liberation.
 
Shri Krishna concludes the topic of Purusha and Prakriti with this shloka.