Death

"aśhochyān-anvaśhochas-tvaṁ prajñā-vādānśh cha bhāṣhase
gatāsūn-agatāsūnśh-cha nānuśhochanti paṇḍitāḥ" - Bhagavad Gita 2.11

As I read the above shloka, my mind is engaged upon the metaphysical concept of Death. What is this Death that instills a painful feeling of fear, anxiety and sorrow in our hearts ? And despite all these feelings that occur naturally to a human being, what is the possible meaning of the above shloka in the context of death ?
Doctors define death as the ceasing of all biological functions of the body followed by gradual decomposition. It is an inevitable experience that each one of us has to undergo for the first and last time in our existence, irrespective of our liking or disliking. We fear death and feel sorrowful even at the thought of the death of our near and dear ones, despite knowing that it is inevitable. For me, the fear of death is the bodily pain that I have to undergo as systematically all my organs stop working. It is the deep fear of darkness and the ultimate oblivion which will swallow all my consciousness. The feelings of sorrow arise when I imagine my near and dear ones mourning near my lifeless body. For them, my body will become another doll which is meant to be destroyed by cremation. Similar feelings do come to my mind when I think about their death. As I imagine all these, I can empathize with the greatest archer Arjuna for feeling reluctant to kill his own kith and kin in a war. Since I have placed myself in Arjuna's shoes, I decided to read on to clarify my clouded mind.
As I read further, my doubts got clarified in the very next shloka

"na tvevāhaṁ jātu nāsaṁ na tvaṁ neme janādhipāḥ
na chaiva na bhaviṣhyāmaḥ sarve vayamataḥ param" - Bhagavad Gita 2.12

Literally translating, this means - "Never was there a time when I did not exist, nor you, nor all these kings; nor in the future shall any of us cease to be."
As I read this, I looked at my own body. What is this body ? To my eyes, it is basically a huge, but divinely systematical arrangement of elements like carbon, hydrogen, oxygen, nitrogen, calcium and others. The motive power to keep this systematic arrangement stable without disintegrating into the nature is my life-force or soul or electromagnetic energy. When we die, this electromagnetic energy gets dissipated, leaving behind the elements which decompose into nature. This means, that all the elements with their exact atom count remains constant before and after our death. In other words, the atoms and molecules that make up my eyes may be the same ones that once were a part of the thumb finger of Alexander the Great !! So, even after our death we continue to exist in this universe as something else because the total mass and energy of this universe is constant. So should we fear and feel sorrowful about this mere rearrangement of atoms and molecules ??
As I believe, our existence is not merely a coincidence. From a unicellular zygote to a fully grown living organism, we have made this remarkable journey for a purpose - i.e. to actively participate in the divine play of creation, sustenance and annihilation of life on this beautiful blue planet earth. For human beings like us, who live in a civilized society, our responsibilities are more than other organisms. Unlike other creatures who spend their entire lives in eating, growing, mating, propagating and dying, we humans have the additional responsibility of maintaining the civilized order of the society we live in. This is achieved by performing our assigned duties in the various roles we portray in day to day life. For instance, our brave Jawans serving the nation, even to the peril of their lives are our heroes. This is not because they are bestowed with super-powers like Super Man or Spider Man. It is only because, in the line of duty, they prioritize their duties as a warrior over the duties of a father, a husband, a son and a friend. Unfortunately, I am penning down my thoughts because most of us have restricted our roles to only a loving father (Dhritrastra types), a devoted son (Bhishma types), a best friend (Karna types), a loyal employee (Dronacharya types), an over-protective mother (Kaykeyi types) personalities; forgetting the duties of a "Stupid Common Man" who is the base of this civilized society. As He has rightly said -

"niyataṁ kuru karma tvaṁ karma jyāyo hyakarmaṇaḥ
śharīra-yātrāpi cha te na prasiddhyed akarmaṇaḥ" - Bhagavad Gita 3.8