To those who think they are irreplacable I say this - We are all replaceable.
Take a glass of water, put your finger in it, remove your finger and see how big of a hole is left when you remove your finger from the water.
drover
Do that repeatedly and watch the water level.
"No man is an island,
Entire of itself,
Every man is a piece of the continent,
A part of the main.
If a clod be washed away by the sea,
Europe is the less.
As well as if a promontory were.
As well as if a manor of thy friend's,
Or of thine own were:
Any man's death diminishes me,
Because I am involved in mankind,
And therefore never send to know for whom the bell tolls;
It tolls for thee."
John Donne