This is rather profound, actually. Most comics don't deal with the mysteries of death in a realistic manner - they either have a set heaven and hell that regularly spew out ghosts and devils and whatnot, or they say 'nope, there's no afterlife, and this proves it, nyah nyah'. (Which, frankly, I always find to be a little annoying - I'm not too fond of ultra-religious types, but at least they generally aren't SMUG about their beliefs.) Having death explored on the level that most people who aren't either particularly religious or particularly rationalist experience it - i.e, that we don't KNOW, that it's almost impossible to prove anything one way or the other - is rare, and it looks to be handled well here.