The primary cause for a Thermodynamic System to appear is the theory leading to understanding of the idea “Thermodynamic System”. This is contrary to the common belief, where we think that theories come out of things, and not the other way around. If it was true that theories were based on things and not the other way around, then things would inherently have their names. Where as actually we give things their names. This proves that when we say “car” it is really so that by saying car we create the thing “car”. If we never said it, then it would never had appeared. This way also, the only way to have a Thermodynamic System to appear, is by first creating a theory that gives that particular kind of system the power to appear.
Such is the nature of all theories, words, systems and things.