Introduction of currency eliminates the 'double coincidence of wants' problem.

Price discovery through the interaction of supply and demand curves.

The continuous flow of money, goods, and services between households and firms.

Energy as the fundamental enabler and constraint of economic activity. All economic work requires energy transformation.

Economy as a dissipative structure: order maintained through energy throughput. Entropy as the ultimate constraint.

Exponential growth meets finite resources. The dynamics of overshoot and collapse.

Economy as emergent behavior of interacting agents. Self-organization, feedback loops, and phase transitions.