ode to the indispensible man (or woman)

Sometimes when you're feeling important,
Sometimes when your ego's in bloom,
Sometime when you take it for granted
you're the best qualified in the room,
Sometime when you feel that your going
would leave an unfillable hole.
Just follow this simple instruction
and see how it humbles your soul.
Take a bucket and fill it with water
put your hand in it up to the wrist,
pull it out and the hole that's remaining
is a measure of how much you'll be missed.
You may splash all you like when you enter
you can stir up the water galore.
But stop and you'll find in a minute
that it looks quite the same as before.