General systems theory is considered as a formal theory (Mesarovic, Wymore), a methodology (Ashby, Klir), a way of thinking (Bertalanffy, Churchman), a way of looking at the world (Weinberg), a search for an optimal simplification (Ashby, Weinberg), didactic method (Boulding, Klir, Weinberg), metalanguage (Logren), and profession (Klir).