World models in circle forms: abstract concepts
The basic models of figures (shapes) have been transferred to the world of abstract concepts as well.
Circles have become essential for the concept of (en)closedness. This form appears in the sacral architecture and earthen pots of the stone age ten thousand years ago, then later in art and even in the last century’s mathematics.
It is something like this how our minds create abstract images in different and more and more general levels. Probably, these model mechanisms of abstraction are what create the conceptual system of arts, harmonies and disharmonies, styles, common and individual characteristics.
Control engineering, when examining phenomena which are infinite in time and space, i.e. which are unobservable and uncontrollable by us, acts similarly: it transforms the infinite span of time and space into a closed circle and carries out the necessary operations and examinations there. This topic will be elaborated in more detail in the chapter about controls.