(iv) The fourth level is that of the "open system," or self-maintaining structure... - Kenneth E. Boulding

Every culture, or subculture, is defined by a set of common values, that is, generally agreed upon preferences. Without a core of common values a culture cannot exist, and we classify society into cultures and subcultures precisely because it is possible to identify groups who have common values.

Knowledge exists in minds, not in books. Before what has been found can be used by practitioners, someone must organize it, integrate it, extract the message

We cannot walk befor we toddle,
Though we may toddle far too long,
If we embrace a lovely Model
That is consistent, clear, and wrong.
- Experts from "Notes from Wooods Hole", unpublished, 1976.