General, your tank is a powerful vehicle

General, your tank is a powerful vehicle.
It smashes down forests and crushes a hundred men.
But it has one defect:
It needs a driver.

General, your bomber is powerful.
It flies faster than a storm and carries more than an elephant.
But it has one defect:
It needs a mechanic.

General, man is very useful.
He can fly and he can kill.
But he has one defect:
He can think.

— Bertolt Brecht