In the Katha Upanishad, it says that Death is the thing which eats the entire universe, yet to one who knows what he is, death is just a pickle - it's the condiment which helps the enjoyment and zest of life.
To the one who takes the world as a collection of things, of independent existences, death is tragic. Death is the snuffing out of existence, the dissolution of something which exists - independently. It was here, now it's gone. Death is that which dissolves existence - in other words, death is the ending of existence for each independent thing.
For one who knows what he is - death is a pickle. Death is that coming and going of patterns - death is the play of Life - a character walks onto the stage, stays a while, then leaves stage left. From the perspective of the viewer, the character ceases. From the perspective of the director, the actor merely stopped performing. From the perspective of the story, that character ceases to exist. From the perspective of the actor, existence remains.
There is one essence, one IS-ness - one "existence" - that essence is expressing in an infinitude of ways - from the tadpole to the cell biology to the pull of gravity - the rock and the tree and the birdsong. Each experience is a patterning OF something which IS - the rock or the tree or the cell is merely that IS-ness which has formed, patterned, taken it's place on the stage of experience. It remains for a while then departs, dissolves, ceases to pattern - we cannot truly say it ceases to exist, except from the perspective of the experiencer of that pattern. It's death is merely a ceasing to appear, a ceasing to pattern, and not a ceasing to exist.
We look upon the world in the normal way - taking each thing that appears as an absolute existence, a stand-alone existence. It is a new existence on it's own - this is a key point which must be grasped. This is our belief which is the most cherished. It is almost impossible to even challenge or doubt it, however at root it is the basis of Maya - taking the world to be a collection of separate existences.
When we see death as the ending of existence, then we are afraid - we don't want to lose what we have and we dread the ending of our own existence. Yet if we just begin to poke into these ideas about existence- if we truly look to discover the actual nature of anything that appears, anything we can know - if we question the idea that existence is something which can come and go after all - then we are on the right track.
Death is a pickle - it is the condiment which makes the meal taste better - the meal is the play - the enjoyment of this transient Consciousness - as long as Consciousness comes and goes -the world comes and goes. Each thing appears - to take those things as absolutes of themselves is Maya. To know they are merely appearance, merely patterns OF something which EXISTS - something which remains while it's expressions come and go, like the waves on the ocean, then we understand the meaning of this Katha Upanishad and we enjoy the meal even as death ravishes the world.