Von Neumann proved the theoretical existence of economic equilibrium. His assumptions explain also how and why cycles are generated. Two features of the model, reflecting the operation of the market, trigger these. The first feature is a non-focal equilibrium that takes place at a saddle-point, maximizing production while minimizing the rate of interest or monetary gain. The second is the inevitability of cross-regulation. Surplus gain boosts production while excess supply curbs prices.