KATHOPNISHAD CHAPTER 2 SHLOKA-22

                                                   अशरीरँ शरीरेष्व-नवस्थेष्ववस्थितम् । 

                                             महान्तं विभुमात्मानं मत्वा धीरो न शोचति ॥ २2

                       ASHARIRAM SHARIRESHU ANAVASHTYETU AVASHTHITAM |

                 MAHANTAM VIBHUM ATMANAM MATVA DHIRO NA SHOCHATI ||22

THE WISE MAN - OR ENLIGHTENED MAN WHO KNOWS THAT THE ATMAN AS WITHOUT 

   BODY BUT FIRMLY SEATED IN PERISHABLE BODY IS GREAT AND ALL PERVADING

                                -(SO THE WISW MAN)DOES NOT GRIEVE||22

     In this SHLOKA, the Lord of DEATH is teaching the principle of death and mortality. If you recollect ,Nachiketa had asked Yama as to what is the truth when some say he is gone - dead and other say not gone .So the answer is the body is perishable  and gone at the time of death but the Atman is not -The  question may arise as to what is body -Is it it just the physical body or the mind, intellect and ego  and CHITTA -are also perishable. The answer is not in this Shloka. But as I understand it, the mind, intellect  and are part of PRAKRUTI  and not part os PYRUSHA  and so are in that way perishable. But the main conclusion is that the Atman is not perishable  and it not only stays in perishable body but also pervades everything. So this is difficult to understand as if something can be limited by physical body, how can it pervades everything or be limitless . But it is . Also the ego is ignorance ridden Atman that confines or confuses the physical body to be the SELF or Atman. 

     In Hindu philosophy we have 2 main groups. In one the Purusha is the only reality and Prakruti is not .In other group the Purusha and Prakruti are both independent Realities .But one can not do without other.

   But the main understanding of this Shloka is that ATMAN is Immortal an is All pervading and does not die when the physical body dies.