EN
The operation and disturbances of the US stock market around the turn of the millennium were treated in detail by Shiller (2000) and Soros (2008). Since the present protracted and general depression will have deep effects on the operation, theories and regulation of the economy, it is worth re-examining the forms in which it developed. The study puts forward a mathematical line of argument, but without formulae or equations, concerned with the operation of the economy, its pattern of movement, and the scope for modelling it. The flexibility of the group of models describing the mutual financial effects allows a better fit and forecasting ability than before, while revealing the theoretical roots of the present difficulties.