Summary: The Spirit of Laws (page 3)
In a monarchy, power belongs to a single ruler—as it does in despotism. What distinguishes the two is the presence, in a monarchy, of various subordinate intermediate powers, notably the nobility. In despotism, there are none. The despot's power is exercised directly over everyone, leaving no authority to anyone else.
The nobility is therefore essential to a monarchy: it is what prevents the king's power from descending into despotism. The fundamental maxim of monarchy is accordingly:
No monarch, no nobility; no nobility, no monarch, but we have a despot 1.
Attacking the nobility is the surest way for the people to overthrow a monarchy—but it will only be replaced by despotism. Similarly, while the power of the clergy is dangerous in a republic, it is useful in a monarchy, where it can act as a check on the monarch's arbitrary power.
In despotism, a characteristic pattern generally prevails: the ruler delegates his power to a subordinate—a vizier—who manages all affairs of state, while the ruler himself devotes himself to pleasure and a life of indulgence.
This is the fundamental law of despotism.
Book III: The Principles of the Three Governments
Montesquieu deduces the principle of each of these three governments from their respective natures, as outlined above.
If the nature of a government is what determines its structure, its principle is what drives its actions—the human passions that animate it.
In a democracy, power belongs to the people or to part of the people. Since they will be called upon to decide on laws that directly affect them, those who vote must possess enough virtue to support laws that may even penalise themselves.
The virtue of citizens is therefore the essential principle of democracies.
Virtue is not the principle of monarchies, since the monarch decrees laws to which he is not himself subject. He does not need to be virtuous.
This does not mean that virtue is entirely absent from monarchies, but simply that a monarchy can sustain itself without it—as can despotism.
Montesquieu illustrates this with several historical examples. Take the case of England: it was the corruption of its leaders that prevented it from ever establishing itself as a democracy. Likewise, Sylla was unable to restore democracy to Rome after his dictatorship because the city was too corrupt.
Athens defeated the Persians and Sparta with 20,000 men because its citizens were virtuous. Later, it lost with those same 20,000 men to Philip. What caused their defeat, despite having the same forces? The lack of virtue among the citizens.
Montesquieu thus describes the gradual decline of civic morals in a republic that loses its virtue:
We were free with the laws; now we want to be free against them. Every citizen is like a slave who has escaped from his master's house. What was once a maxim is now called oppression; what was once a rule is now called a hindrance; what was once vigilance is now called fear. The republic is a corpse 2.
The principle of aristocracy is similar, because the nobles, like the people in a democracy, must decide on laws that will affect themselves. They too must be virtuous—but to a lesser degree. Montesquieu calls this virtue moderation. Moderation is therefore the principle of aristocracy.
Virtue is not the principle of monarchy. Just as the finest machines are those with the fewest moving parts, a monarchy achieves the greatest things with the least possible virtue.
The state functions without love for the fatherland or self-denial: The laws take the place of all these virtues, which are no longer needed—the state dispenses with them
3.
1 II, chap. 4
2 III, chap. 3
3 III, chap. 5