 Plato and Aristotle hold a cyclical view of human affairs.  They allow that certain developments occur spontaneously, but also see disaster and decline as inevitable.  In the Laws, Plato proposes that human society begins with the family, then moves through intermediate forms, and finally arrives at the city-state (680a-682d).  In the Politics, Aristotle also presents this progression of forms (1252a24–1253a4).  Not only is man a political animal as a matter of fact (Politics, 1253a2), it is also true that human excellence is only possible within a city-state with a good constitution.  But unhappily there is no tendency for the city-state, once achieved, to realize or maintain such a constitution.  For instance, while Aristotle cautiously admits that laws can and should improve (1269a12–14), Book V of the Politics shows that all constitutional forms—bad and good—are unstable. 