Forrester notes that the classification of a system as either open or closed depends upon the perspective of the system observer. For example, a car would be classified as an open system if it has no cruise control and is being observed by a driver who does not consider himself to be part of the system. From this perspective, the amount the gas pedal is depressed (the input) influences the car's speed (its output), but the car's speed does not influence how much the gas pedal is depressed. --- MORE --->