Aristotle involved empirical method (based on observation by five senses - sight, sound, smell, test and touch, and not speculation) of studying politics and combined it with the comparative method . He sent his disciples to different places of the world for making case histories of constitutions thereof. Accordingly, they prepared 158 cases histories . Aristotle himself observed them and concluded with the following forms of constitutions:- Cycle of change of governments - Aristotle holds that no form of government is in the purest form and stable. They keep changing overtime for following reasons:- Monarchy is good in normal circumstances. But when the absolute power of a monarch grows enormously and goes beyond limits it takes up the form of tyranny because power and virtue cannot go together. But tyranny is soon overthrown by elected few, and aristocracy is set up. In the absence of any effective curbs on their power, aristocracy degenerated into oligarchy . Soon, a large nu