ABSTRACT
Most, if not all, economics is dominated by the notion of equilibrium. The subject matter of economics is so complex and in any situation there are so many possibilities that we need some systematic way of ruling out many of these possibilities and concentrating on a few about which we can make some plausible predictions. Equilibrium is the notion which helps us with that. Away from equilibrium anything is possible; in and around equilibrium, only a few things are possible.
