“An internal combustion engine is 'clearly' a system; we subscribe to this opinion because we know that the engine was designed precisely to be a system. It is, however, possible to envisage that someone (a Martian perhaps) totally devoid of engineering knowledge might at first regard the engine as a random collection of objects. If this someone is to draw the conclusion that the collection is coherent, forming a system, it will be necessary to begin by inspecting the relationships of the entities comprising the collection to each other. In declaring that a collection ought to be called a system, that is to say, we acknowledge relatedness. But everything is related to everything else. The philosopher Hegel enunciated a proposition called the Axiom of Internal Relations. This states that the relations by which terms are related are an integral part of the terms they relate. So the notion we have of any thing is enriched by the general connotation of the term which names it; and this connotation describes the relationship of the thing to other things… [There are three stages in the recognition of a system]… we acknowledge particular relationships which are obtrusive: this turns a mere collection into something that may be called an assemblage. Secondly, we detect a pattern in the set of relationships concerned: this turns an assemblage into a systematically arranged assemblage. Thirdly, we perceive a purpose served by this arrangement: and there is a system.”

Source: Decision and control: the meaning of operational research and management cybernetics, 1966, p. 242.