Ludwig von Bertalanffy

a.      “Thus, there exist models, principles and laws that apply to generalized systems or their subclasses, irrespective of their particular kind, the nature of their component elements, and the relations or "forces" between them.  It seems legitimate to ask for a theory, not of systems of a more or less special kind, but of universal principles applying to systems in general.” Page 32

b.      “A verbal model is better than no model at all.  Models in ordinary language therefore have their place in systems theory.  The system idea retains its value even where it cannot be formulated mathematically or remains a "guiding idea" rather than being a mathematical construct.” Page 24

c.      “It looks, at first, as if the definition of systems as "sets of elements standing in interrelation" is so general and vague that not much can be learned from it.  This, however, is not true.” Page 38

d.      “Systems Theory also is frequently identified with cybernetics and control theory.  This is again incorrect.  Cybernetics, as the theory of control mechanisms in technology and nature and founded on the concepts of information and feedback is but a part of a general theory of systems;  cybernetic systems are a special case, however important, of systems showing self-regulation.”  Page 17.

e.      "A general theory of hierarchic order obviously will be a mainstay of general system theory."

f.      "Thus there is an array of system models more or less progressed and elaborate."

g.      "As practice in applied systems analysis shows, diverse system models will have to be applied according to the nature of the case and operational criteria."