Shankaracharya is discussing the last series of Jñāna yoga namely, Nidhithyasanam.  Nidhithyasanam is of two types: 

• One is withdrawing all transactions and dwelling up on the teachings of Upanishads, especially those aspects which are very relevant to me. 
• The second type of nidhithyasanam is constantly alert through all my transactions so that my responses and reactions are not contrary to vedantic teaching. This goes along with life.

The Fourth mantra gives instructions for nidhithyasanam; these instructions promote nidhithyasanam.  In the fifth mantra, Sankarachariyar is talking about nidhithyasanam itself.  Seated in a secular place, mind fixed up on brahman or atma, very clearly see the fact that atma is poorna; I don’t lack anything in life; I am self-sufficient.  However, as long as the anatma world is there, atma can’t be poorna.  As long as I see anatma as different from me, I the atma will be different.  Sankarachariyar says that may you negate anatma (the world) in the vision of atma.  How is it possible?  By seeing atma as karanam, sathyam and seeing anatma as karanam mithya.  Anatma is taken as solid reality until I discover atma; in the discovery of atma, anatma is reduced to nama roopa.  This world is negated with the vision of atma.  Once a person has practiced nidhithyasanam for sufficient amount of time, jñāna nishta comes.  Once jñāna nishta has come, this vision is spontaneous.  This is called jivan mukthi.  Once this spontaneous has come, even nidhithyasanam is not required.  Until this spontaneous is achieved, nidhithyasanam is required. 

Lead a life of jivan muktha and at the time of death videha muktha.  But to understand jivan muktha and videha muktha, Sankarachariyar introduces the threefold karma:  Sanjitha karma, agami karma and prarabtha karma.

Principles constitute the laws of karma:

1. Every action has two types of results known as dhrishtam (visible result) and adhristham (invisible result).
2. The invisible result is of two types: punyam and pavam.
3. Which action produces punyam and which action produces pavam is determined by sastra.  Whatever actions commanded by sastra produce punyam and whatever action prohibited by sastra produce pavam. 
4. The invisible punyam and pavam will later give pleasurable and painful experiences. 
5. The gap or the duration required for punyam to produce pleasure is unpredictable by us.  The punyam’s incubation period is inherent in punyam itself.  Similarly, the incubation period of pavam is also not predictable by us.  This is like different seeds sprouting after different duration times. 
6. Since the time taken can’t be predicted by us, some of the punya pavam may not fructify in this jenma because of which an individual dies with punya pava balance. 
7. To experience the balance punya pavam one requires punar jenma.  In the next jenma, even though we exhaust some of the pava punya, we accumulate more punya pavam.  In next jenma more punya pavam.  Thus, every jiva has huge stock of pava paunya accumulated in the past countless jenma. 

All the accumulated punya pavam are called sanjitha karma.  Out of this sanjitha karma, only a portion is ready for fructification.  That portion is called prarbtha punya pavam, which alone is responsible for present birth, condition of present body, duration of life etc. When we are exhausting the prarbthamm in the current jenma, whatever fresh punya pavam we acquire is called agami.  In the agami also, some portions may fructify in this jenma itself.  Some of the agami karma do not fructify in this jenma and they will join the sanjitha karma at the time of death.  This sanjitha karma will result in the next jenma.  This the cycle of an ignorant man. 

This law of karma is not proven by science.  Laws of karma are accepted by us based on sasthra alone.  The benefit of accepting this law of karma is:

1. The law of karma alone explains the disparity in the world, disparity among human beings.  The law of karma explains the difference in human beings, animal etc.
2. The law of karma helps in accepting some of the painful experience for which we don’t see any immediate reason.  The effect is visible, but the cause is not visible; but it is in the form of prarabtha pavam; therefore, we don’t see the injustice in my suffering.   I accept that I am suffering because of my past pavam. The law of karma is a great shock absorber.
3. If I accept the law of karma, I can take charge of my future.  Because I know I am responsible for my current situation and future situation; it is not determined by fate, chance, or God, but it is determined by me.  The present me is the product of the past me and future me is the product of current me.  Therefore, I can take charge of the future.   If the law of karma is not accepted, then everything is determined by chance, then the future is also determined by chance.  Then why should I work for a better future?
4. We can introduce moral order in society only with the help of the law of karma.  Because one of the questions is that why are many corrupt people thriving, while moral, conscientious and righteous people suffer.  The conclusion may be that if you have to thrive, you will have to be corrupt.  If you are good, then you will suffer.  We can break this disparity of equation only with the law of karma.  The corrupt person is thriving not because of corruption, but corruption will result in pavam; we don’t know when it will fructify.  If a noble person suffers, it is not because of nobility, but because of prarabtham.

In the case of jñāni, by the strength of the knowledge, he dissolves sanjitha karma like a dreamer resolving all the karma by waking up.  May you not be affected by the agami karma because of your lack of ego.  Just as the lotus leaf is not affected by the water.  Sanjitha is burnt and insulated from agami.  Karma will produce pavam at vyāvahārika level.  The prarabtha is exhausted in this jenma itself.  There will be suga dhukka experiences, but he will not claim them to be his.  In front of the atma awareness, all this will appear insignificant.  Ahamkara suffering is huge when you see it as yours, but when you see it from atma, it will appear insignificant. Jñāni goes through the same problem as everyone else, but because of his higher level, they appear insignificant.

After the prarbtha has been exhausted, may you remain eternally as pram brahman.  What has gone is ahamkara, but jñāni or atma is the primary illuminator, Brahman.  After the death of jñāni, the primary illuminator, the atma continues.  The difference is when the pot was around, the space was given the name pot space.  When the pot is broken, the name pot space is gone.  Similarly, when the body is alive, there is a name; when the body is gone, the name is gone but the atma continues.  He remains as brahman; and this is videha mukthi.

Whether a person goes through all the ashramas, one has to go through physically or not, one must go through the four stages mentally and or mentally and physically and attain jivan mukthi and videha mukthi.