When endeavoring to develop an understanding of the nature of something it is generally useful to create a model of some type to aid in surfacing that understanding.
If we pay close attention to our actions and the typical outcomes of those actions it would be evident that there are frequently occurring patterns that develop. And there is a relation between the patterns.
The model construction process is actually a balancing loop which endeavors to employ an abstract version of real events to form a model which produces conclusions and behavior which mimic the real events.
Consider the following "Sustaining the Forest" model intended to provide another example of how unexpected the behavior of a web of extended interactions can be.