Just as there are inputs which are supplied by the owner of a business, and whose value therefore is a "virtual," not an actual, expense, so there ca… - Kenneth E. Boulding

Two possible approaches to the organization of general systems theory suggest themselves, which are to be thought of as complementary rather than competitive, or at least as two roads each of which is worth exploring. The first approach is to look over the empirical universe and to pick out certain general phenomena which are found in many different disciplines, and to seek to build up general theoretical models relevant to these phenomena. The second approach is to arrange the empirical fields in a hierarchy of complexity of organization of their basic "individual" or unit of behavior, and to try to develop a level of abstraction appropriate to each.

:(ii) The next level of systematic analysis is that of the simple dynamic system with predetermined, necessary motions...

It is almost as hard to define mathematics as it is to define economics, and one is tempted to fall back on the famous old definition attributed to , “Economics is what economists do,” and say that mathematics is what mathematicians do. A large part of mathematics deals with the formal relations of quantities or numbers.