that is Montesquieu's central doctrine. There is no one best form of state or constitution: no law is good or bad in the abstract. Every law, civil and political, must be considered in its relations to the environment, and by the adaptation to that environment its excellence must be judged. If you wish to know and understand the spirit of a law, its essence, its true and inner meaning, that on which its vitality and efficiency depend, you must examine it in its relations to all its antecedents and to all its surroundings. This is the theme which Montesquieu tries to develop and illustrate in the course of his book.
He begins with the relations of laws to different forms of government. There are three kinds of government—republics, with their two varieties of democracy and aristocracy, monarchies, and despotisms. The threefold division is, of course, as old as Plato and Aristotle, but the mode of distribution is new, and is not easily to be defended on scientific grounds. But the historical explanation of the distribution is quite simple. Montesquieu was thinking of the three main types of government with which he was familiar through study or observation. By a republic he meant the city states of the Greek and Roman world, and also such modern city states as Venice and Genoa. Monarchy was the limited monarchy of the West, which still preserved traditions of constitutional checks, but which was, in most countries, tending to become absolute. Despotism was the unbridled, capricious rule of the eastern world.
Each form of government has its peculiar principle or mainspring. The principle or mainspring of democracy is virtue (by which he practically meant 'public
