If it wasn't for the pessimist
What would the optimist do
They'd have no earthly idea
What was needed to pull through

Or the gravity of the situation
And how to handle it best
Without the negative of the pessimist
What would fill the optimists head

Without the doom and gloom of the pessimist
Positive would be a lost cause
My best guess is that the optimist
Needs the pessimist after all