Mihajlo D. Mesarovic Quote
Since it can be argued that both science and engineering are concerned with the study of real systems and their behavior, it follows that a general theory should be concerned with the study of general systems... It suffices for the present discussion to consider a general system as an abstract analogue or model of a class of real systems. General systems theory is then a theory of general models.
Mesarovic (1964) cited in: Shatrughna P. Sinha (1991) Instant encyclopaedia of geography. 1. Introduction to geography. Mittal Publications, p. 467