Donella Meadows

This reinforcing feedback loop is the central engine of growth in an economy.

The concept of feedback opens up the idea that a system can cause its own behavior.

Resilience, self-organization, and hierarchy are three of the reasons dynamic systems can work so well.

To be a highly functional system, hierarchy must balance the welfare, freedoms, and responsibilities of the subsystems and total system—there must be enough central control to achieve coordination toward the large system goal, and enough autonomy to keep all subsystems flourishing, functioning, and self-organizing.

Hierarchical systems evolve from the bottom up. The purpose of the upper layers of the hierarchy is to serve the purposes of the lower layers.

Everything we think we know about the world is a model. Our models do have a strong congruence with the world. Our models fall far short of representing the real world fully.

Events are the outputs, moment by moment, from the black box of the system.

long term behavior provides clues to the underlying system structure. And structure is the key to understanding not just what is happening, but why

System structure is the source of system behavior. System behavior reveals itself as a series of events over time.

There is no single, legitimate boundary to draw around a system. We have to invent boundaries for clarity and sanity; and boundaries can produce problems when we forget that we’ve artificially created them.