I think death emotionally brings us back to a very early time in
our lives, before we had words and had only uncertain emotional
responses and a world and body and mind that just didn't make
sense;
One of the first lessons we learn is permanence of objects.
Peek-a-boo. "Guess what? your ball is still here!" "Guess what?
Mommy's still here."
One day, there's death in your life and you're aware that
peekaboo was a lie. One of your first learning experiences shot
to hell and all you can do is go back to the emotional state of
your first loss, the no-words sensation - the existential crisis
of object impermanence - and the initial trust gained that was
then broken.