Preamble
We  have seen the dejection of Arjuna and his determination not to wage the war.  Since Bhagavan Krishna has discovered that the deep-rooted delusion and grief  of Arjuna cannot be removed without the knowledge of reality, He immediately  starts His discourse on the immortality of the Soul with a virtual smile on His  face,

In  that moment of depression, the sinking heart of Arjuna heard the Divine voice  of Krishna. Krishna’s virtual smile indicates that he saw through Arjuna’s  attempt at rationalization of what is now known as wishful thinking.

Krishna  starts the sermon of the Gita by stating that:
1. The wise grieve neither for the living nor for  the dead.
2. The Self within is eternal, indestructible.
3. The bodies enveloping the Self are ephemeral.  They have a beginning and an end.
4. Death is certain for the born and birth for the  dead.
5. Beings constantly pass through the repeated  stages of unmanifest, manifest and again unmanifest. So why grieve over the  inevitable?
6. The indwelling Self remains eternally the same.

The  2nd Chapter is considered as the epitome of all that stands for in  the Gita.

The  Text

THE DISTINCTION BETWEEN THE SELF  AND THE BODY:
  WE SHOULD NOT GRIEVE FOR WHAT IS  IMPERISHABLE.

sri  bhagavaan uvaacha
    ashochyaan  anvashochastwam prajnaavaadaamshcha bhaashase
    gataasoon  agataasoomshcha naanushochanti panditaah   // 2.11 //

Sri  Bhagavan said
    You grieve for those  who are not to be grieved for; and yet you speak words of wisdom! The learned  do not grieve for the departed and those who have not departed.

There are four  propositions in this verse. 1.Arjuna is grieving 2. He is grieving for those  not to be grieved for. 3. He speaks the words of the wise though he is not so,  and 4. The wise do not grieve for the living or for the dead.

Let us have a closer  look at these statements.

1. The cause for Arjuna’s suffering and distress is because  when he looked at his relatives, friends and teachers lined up on the opposite  side, the feeling of ‘me’ and ‘mine’ became very strong in him, the central  point being the sense of ‘I.’ A man is  grieved when he categorizes some objects or persons as his own and some others  as not his own. This sense of mine and not-mine - attachment for things  considered as one’s own and indifference for things considered as not one’s own  - is called ego which is the source of all grief, worry, fear and confusion.  Rediscovering oneself to be really higher than one’s ego is the end of all  sorrows arising out of false identification or relationship.

So Krishna went to the bottom of this grief, sorrow,  misery and suffering and explained that a wise man does not have the sense of  ‘I’, ‘me’ and ‘mine’. Such a man is not bound by any tie or attachment of any  kind.

2. Here the phrase ‘those not to be grieved for’ refers  to Bhishma and Drona.Why they are not to be grieved for? It is because they are  beyond the sense of attachment and the feeling of “I’ ‘my’ and ‘mine’. That is  the reason why they are on the side of the Kaurava army despite the Pandavas  being equally dear to them. They are aware of the difference between the real  and the unreal, the soul and the body respectively. They are wise because they  have realized the eternal reality behind the phenomenal changes and therefore  do not grieve at the decay and death of the finite and the mortal in the form  of the physical bodies.

When we go to the sea shore we do not grieve over each  wave that rises and dissolves for we know that they are unreal and the real  thing is the water in the waves. Waves are like the physical bodies which  appear and disappear while the indweller of the body, the self or soul is like  the water. Those who have realized this eternal truth have no sorrow for the  change they perceive in the world of happenings.

Thus both real and unreal are not to be grieved at as the  real is imperishable and therefore should not be grieved for. The unreal is  bound to perish, as it is perishing at every moment, so it should not also be  grieved at. It follows that Arjuna’s grief over the bodies of his relatives  getting perished is misplaced and is the consequence of his ignorance, lack of  right knowledge, avidya although his words apparently look wise which in  fact they are not. Hence Krishna says that he is grieving for those who should  not be grieved for.

What Krishna means is “Arjuna, Look at those standing  before you not as human beings; look at them as the souls (atman) and  the soul is immortal; you cannot kill the soul if you have the real knowledge”.  The idea is, “You are sorrowing for those who are eternal in the real sense,  and therefore who are not to be grieved for. Hence you are a fool”.

 “The wise do not mourn for the dead or for the  living,” says Krishna to Arjuna. Why? Because there are no “living” or “dead”  in the sense that those with bodies are alive and those divested of a body are  dead. Nor is there such a duality called life and death. These are only the  illusions produced by the distorting veils of ignorance. “Lead me from death to  immortality” is not a petition to gain a state where we will nevermore  experience bodily death, but a plea to be led from the outward-turned  consciousness that produces death to the inward-turned consciousness that  produces life. It is spirit itself that is immortality–nothing else.

In  order to remedy this myopic view of Arjuna, Krishna administered the strongest  medicine of the Knowledge of the Self to him at the very first stroke from the  11th verse of this chapter which is considered as the key verse of the Gita. All  the subsequent teachings are an elaboration of the principle laid down in this  verse.

He  advised Arjuna to renounce his physical, emotional and intellectual estimate of  his grand-sire and teacher and to re-evaluate the situation from his spiritual  understanding whereby his problem at the battlefield would vanish.

na  twevaaham jaatu naasam na twam neme janaadhipaah
    na  chaiva na bhavishyaamah sarve vayam atah param // 2.12 //

It  is not that I did not exist before, nor you nor these kings.  Nor is it that we shall cease to exist in  future.

There  are two things in the world, the soul which is real and the body which is  unreal. Both of these are not to be grieved for because the soul never ceases  to be and the body is ever perishable. Thus Sri Krishna speaks here of the  immortality of the Self or the soul. The Self exists in the three periods of  time - past, present and future.

He  declares that the embodied soul in every one identifies itself with varied  forms temporarily to gain preordained experiences. Neither Krishna himself nor  Arjuna nor the other kings who have assembled in the battlefield are mere  accidental happenings nor shall they cease to exist in future. It is not that  they came from nowhere nor at their death they become nothing or  non-existent.  The soul remaining the  same, it gets apparently conditioned by different body equipments and comes to  live through its self-ordained environments.

All  the living creatures existed before their birth; they exist now and would exist  even after the disappearance of their present bodies. A man experiences his  existence before sleep, after sleep and during sleep.  While his existence is continuous, his body  is changing every moment and ultimately perishes one day.  Thus existence is beyond time while biological  body is bound by time and space. Waves arise, they play and die away. But the  ocean ever remains the same.

Prior  to the pot, in the pot and after the pot it was only the mud or clay which has  continuous existence. Just as the destruction of a pot does not lead to the  destruction of clay, so also destruction of the physical body does not lead to  destruction of the Soul. Therefore, Arjuna should not grieve for his relatives  out of fear of their destruction.