Stafford Beer asserts that “control is an attribute of a system”[1], whereby identifying a system to be “in control” means that “it is ultra-stable: capable of adapting smoothly to unpredicted change.”[2] In other words, a system in control can maintain its equilibrium state, adapting to unpredicted changes. It follows that if a system contains a “controller” function, as long as it can control the multitude of forces it receives, the system will remain in a state of equilibrium, or if displaced or agitated, the control function will return to its original one or seek to reach another state of equilibrium. Therefore, the controller’s critical objective in a system is to maintain the equilibrium, or if out of equilibrium, to endeavour to find and reach an equilibrium state.

Moving from a hot environment to a cold one, there is a controller built-in human body that maintains the internal body temperature; and there is a controller that balances the pressure of work with the aggregated satisfactions—monetary, psychologically—being gained.