Donella H. Meadows wrote the following simple, eloquent description of a system:
“A system isn’t just any old collection of things.
A system must consist of three kinds of things: elements, interconnections, and a function or purpose.
A system is an interconnected set of elements that is coherently organized in a way that achieves something.
The behavior of a system cannot be known just by knowing the elements of which the system is made.
A system is more than the sum of its parts.
It may exhibit adaptive, dynamic, goal-seeking, self-preserving, and sometimes evolutionary behavior.
It is easier to learn about a system’s elements than about its interconnections.
If information-based relationships are hard to see, functions or purposes are even harder.
A system’s function or purpose is not necessarily spoken, written, or expressed explicitly, except through the operation of the system.
Purposes are deduced from behavior, not from rhetoric or stated goals.
The least obvious part of the system, its function or purpose, is often the most crucial determinant of the system’s behavior.
To ask whether elements, interconnections, or purposes are most important in a system is to ask an unsystemic question.
All are essential.
All have their roles.
But the least obvious part of the system, its function or purpose, is often the most crucial determinant of the system’s behavior.”
Meadows, Donella H., 2008.Thinking in systems: A primer. Chelsea Green Publishing.