Preamble

Last time we studied up to verse 2.22 dealing with Krishna’s  exposition about the permanent nature of the Soul and the impermanent nature of  the physical body wherein the Lord proved it unreasonable to grieve over the  process of leaving one body and adopting another.

Continuing the discussion from another angle the  Lord in the next three verses reiterates the eternal and changeless character  of the soul and proves that grieving for fear of its destruction is unbecoming  and improper on the part of Arjuna.

The  Text

nainam  chhindanti shastraani nainam dahati paavakah
    na chainam kledayantyaapo na shoshayati maarutah  // 2.23 //

Weapons  cannot cut It, nor can fire burn It; water cannot wet It, nor can wind dry It.

Here  the unseen has been explained by means of the seen to indicate its nature. The  changeless Self is explained with the aid of ever changing world which is  familiar to Arjuna and others.  In the  world of change, objects meet their end by means of instruments of destruction  like weapons, fire, water and wind.

Arjuna’s  grief was based on the assumption that he would be killing the elders and other  realtives by striking them with lethal weapons. Hence in order to remove his  grief the Lord points out the immortality and formlessness of the soul by  pointing out the inability of all the four elements of earth, water, fire and  air to destroy it. The body is perishable and possessed of a form; the soul is  everlasting and formless. Therefore, the soul can never be destroyed by the  elements of earth in the form of weapons or by the elements of water, fire and  air and so it is sheer ignorance to lament for it.

acchedyo'yam  adaahyo'yam akledyo'shoshya eva cha
    nityah  sarvagatah sthaanur achalo'yam sanaatanah // 2.24 //

This  Self cannot be cut, burnt, wetted or dried up. It is eternal, all-pervading,  stable, ancient and immovable.

Continuing  the import of the previous verse, The Lord says that if a thing cannot be  annihilated by any means of destruction discovered by man such an object must  be everlasting.  Since the Self is  indestructible, It is necessarily everlasting. That which is everlasting or  eternal will pervade everywhere. All-pervading indicates that It has only itself  all around It and it is unconditioned by anything other than Itself.
That  which is eternal and all-pervading must be stable meaning no change can ever  happen to It.  That which is stable is  immovable.  Mobility or moving implies  the transfer of an object or person from one set of time and place to another  set of time and place where they were not there already.  Since Self is all-pervading there cannot be  any place or period of time where It was not there before.  As the Self is unconditioned by the concept  of time It is said to be ancient.

Sri  Bhagavan explains nature of immortal Self in a variety of ways giving several  illustrations in order that the underlying idea can be grasped by everybody.

avyakto'yam  achintyo'yam avikaaryo'yam uchyate
    tasmaad  evam viditwainam naanushochitum arhasi // 2.25 //

The  Self is unmanifest, unthinkable and unchangeable. Therefore, knowing it to be as  such, you should not grieve.

The  Self is not an object of perception.  It cannot  be perceived by any one of the senses. Therefore, it is unmanifest. The mind  can think only about an object perceived by the senses. As the Self cannot be  perceived by the senses, It is unthinkable and beyond comprehension.. As the  Self is infinite and without any form it cannot undergo any change.  Hence It is changeless or immutable.

Arjuna's  grief is misplaced as the Self cannot be hurt or slain. Forms may change;  things may come and go but that which remains behind them all is for ever. The  Lord, therefore, advises Arjuna not to grieve on that account and he should not  think that he is the slayer and that the others are slain by him.

IN THE NEXT TWO VERSES THE LORD  SHOWS THAT IT IS IMPROPER TO GRIEVE FOR THE SOUL EVEN IF IT IS ASSUMED TO BE  SUBJECT TO BIRTH AND DEATH.

atha  chainam nityajaatam nityam vaa manyase mritam
    tathaapi  twam mahaabaaho nainam shochitum arhasi // 2.26 //

But  even if you think of it as being perpetually born and perpetually dying, even  then, O Mighty Armed (Arjuna), you should not grieve.

Sri  Krishna, for the sake of argument, takes up the popular assumption here.  Granting that the Self is again and again  born whenever a body comes into being and again and again dies whenever the  body dies, even then one should not grieve, because birth is inevitable to that  which dies and death is inevitable to that which is born.  This is the inexorable law of the nature. As  such, the occasion that Arjuna faces is not the one for lament.

jaatasya  hi dhruvo mrityur dhruvam janma mritasya cha
    tasmaad  aparihaarye'rthe natwam shochitum arhasi // 2.27 //

Death  is sure to happen to that which is born. Birth is sure to happen to that which dies.  Birth and death are certainly  unavoidable.  Therefore you should not  grieve over an inevitable occurrence.

Here  Krishna continues to view the whole situation from the materialistic  angle.  Even from this stand point, if  life is a constant flow of appearances and disappearances one should not shed  tears over the unavoidable.