The contemplation of death is vital for the clarity and enthusiasm for living fully. In particular, reflection on death can be a source of a virtue that helps greatly improve one's peace of mind and quality of life, namely gratitude. [There was a great article recently in UU World on why gratitude should be the defining element of Unitarian Universalism by the way] The Buddhist readers may have heard about various practices for contemplating death, and Christians just recently did so for Easter. I am not sure what elements in other faiths, such as Judaism and Islam, specifically focus on the ramifications of death, but I would be greatly surprised if there were none.
In contemplative mystical terms, including the Buddhist perspective, from the historical perspective, we are born, we live, and we die. In the historical dimension these things are spread out in time and space, and because of this gap, there is a possibility to either not think about death or to not accept that one will die. Those who believe in a literal Second Coming could talk themselves into believing that Jesus will return before they must endure physical death, and besides, they won't really die in a permanent sense anyway. Even those who believe no such thing could believe that genetics and medicine and technology might find some way to use gene therapy to affect the telomeres and somehow makes select people immortal. For those less versed in developmental genetics, there is also the "hope" of cryogenics. But whatever one does, physical death is inevitable. We can slow it, but it will eventually occur, and there is no credible alternative on the table.
And we must die. Why? Well, the answer is deceptively simple - the Buddha is reported to have said that we die because we were born. In Buddhism, the cause and effect are seen as being created simultaneously - however, the effect may be delayed until the proper conditions cause/allow it to manifest itself. Another way to say it is that the price of life is death, the consequence of being born is dying. Again, from the ultimate perspective, that is, taking a "God's eye " view of everything, there is not much distinction. I will be/am being/have been born and I will/am/have died. I may not know the exact point at time in space at which the latter will happen, but for all practical purposes, it's a done deal.
If, indeed, I am (to borrow a phrase) "living on borrowed time", then what about the contemplation of my eventual death? I can visualize myself at a cemetery in front of a headstone, a marble slab with my name craved into it. Tracing the letters with my fingers, the stone is smooth and cold. There is an epitaph, and I can smell the freshly dug soil under my feet. The mist is burning away as the sun rises over the horizon leaving the morning dew on the neatly manicured grass nearby, and a bouquet of flowers is starting to drop a little at the base of the headstone. I have lost everything. My relationships, my health, the use of my body, my money, my career, my possessions - everything. I am just a memory dwelling at the site of the final interment of my remains. Somewhat like Scrooge when visited by the Ghost of Christmas Future, I am faced with the stark reality of my mortality. Eventually even my remains will decay and perhaps be part of other life forms, microbes, or worms, and maybe eventually some of that matter and energy might even find its way into another human being.
And then I am back here, which seems so far away, and yet if these words outlive me, the relative illusion of that distance will be all the more apparent. Pondering this reflection and meditation, it is almost like time travel. I know that I will become ill, and that I will grow old, and eventually die, if death does not not claim me before I become sick or infirm with age, and that the seeming gulf between my current situation and these states of existence is an illusion, a wish, a breeze that plays on my face for a brief moment and then fades away. A blink and I am at my life's end.
So how will I respond? What is my reaction to this realization? What does this mean for my life? I will be grateful. Should I lose my sight or other sense, I will be grateful for the time I had it and all of the things I saw and heard and tasted and felt. Should I lose my limbs, or their use, I will be grateful for the time I had them and the chance to run and jump and swim and climb and romp. Should I lose my health, I will be grateful for all the healthy years I've enjoyed. Each day I will not be upset about what I haven't had or what I've lost, but what I have had and what yet remains, seeing each day as a blessing. And as the moment of my death, if I am conscious, I will be grateful for the chance to live this life.