The bounded rationality of each actor in a system may not lead to decisions that further the welfare of the system as a whole. - Donella Meadows

When there are long delays in feedback loops, some sort of foresight is essential.

In physical, exponentially growing systems, there must be at least one reinforcing loop driving growth and at least one balancing feedback loop constraining growth, because no system can grow forever in a finite environment.

The least obvious part of a system, its function or purpose, is often the most crucial determinant of the system's behavior.