In order that sovereign power may maintain itself, it is important that all citizens meet in periodic assemblies. This may seem unrealistic, but Rousseau points out that in ancient times, even cities as large as Rome managed the feat. If it seems unrealistic today, that is because of the laziness of the people and not because of logistical difficulties. Generally, a state should not be larger than a single town, so assembling the citizens should not be difficult. In the unstable case where several towns are united, Rousseau suggests not having a fixed capital, but rotating the seat of government and popular assembly from town to town.
Though there is no set period of time, Rousseau suggests that the more powerful the government is, the more frequently all citizens should assemble. In such assemblies, the lowliest citizen has as much of a voice as the most powerful magistrate. As a result, these assemblies are a danger to the government, and the government will often try to dissuade the people from assembling. When the citizens are too lazy or reticent to exercise their freedom the government may succeed in undermining sovereign authority.
Often, a population that does not want to assemble to exercise legislative power elect representatives to do their work for them. Rousseau remarks that a state begins to dissolve when the people value comfort over freedom, and pay representatives and mercenaries rather than serve the state themselves. Rousseau derisively speaks of "finance" as the practice of letting one's wallet replace one's duty as a citizen. Representation is a modern idea that evolved from feudalism, and Rousseau re-asserts that sovereignty cannot be represented.
Rousseau notes that the ancient Greeks were able to assemble regularly largely because slaves did most of their work. In the modern world, the people have enslaved themselves by electing representatives to exercise their freedom for them.
Rousseau addresses the institution of government, claiming contrary to the assertion of other theorists that government is not instituted by means of a contract between people and magistrates. First, sovereign power cannot modify itself like that. Second, such a contract would be a particular act, and therefore not a sovereign act. Third, there would be no higher power to ensure that the contract is honored. The decision to institute a government is indeed an act of sovereignty, but the act of assigning certain magistrates is not. Rousseau explains that, momentarily, the sovereign becomes a democracy—a government where every citizen is a magistrate—and the decision to name certain magistrates is a particular act of government. Once magistrates have been named, the sovereign ceases to act like a government, and the government and sovereign become two distinct bodies.
Thus, government is instituted not by contract, but by law, and magistrates are not rulers, but officers. A regular assembly of all the people is the best means of ensuring that the government never usurps sovereign power. At every assembly, the people must vote as to whether the present government and magistrates should be kept in power.
The distinction between government and popular assemblies is absolutely crucial to Rousseau's system. He has already remarked on the friction between government and sovereign: the government that wields power will naturally want to act on its own behalf, and not on behalf of the people as a whole. While in a healthy, happy state, the government can be more or less trusted, some sort of check must exist to keep the government at bay.
This check is the exercise of popular sovereignty. From the beginning of the book, Rousseau has spoken about the sovereign as the expression of the general will and the true voice of the people, but only here does he state explicitly how the general will is to make itself heard. There should be an agreed-upon period of time, written into the constitution, where all citizens must gather together in an assembly and voice their concerns collectively. During this time, government is disbanded. After all, the government as executive is meant to represent the people, and when all the people are present, there is no need for representation. One of the matters discussed at every assembly is the performance of the government and whether it should be allowed to continue. This allows the people collectively to place a check on the government, preventing it from acting against their interests.
Rousseau probably got this idea of checks and balances between executive and legislative from Montesquieu, whose influence he acknowledges at other points in The Social Contract. Montesquieu's idea of dividing government into executive, legislative, and judicial functions, and establishing a system of checks and balances between them, is most famously put into practice in the American constitution.
The demand that all citizens should participate in popular assemblies is unique to Rousseau in the modern world. It is a very tall order, but one that is essential, Rousseau believes, to maintaining a healthy state. He has already stressed the importance of liberty and equality, and with the idea of the popular assembly he stresses the importance of fraternity. "Liberty, equality, fraternity" was to be the motto of the French Revolution, which drew a great deal of inspiration from his ideas.
Naturally, it is in the government's best interests to discourage popular assemblies: without them, the government's power is almost unlimited. For this reason, Rousseau insists that it be written in law that the people must assemble on a regular, periodic basis. Though this law can combat the selfish designs of the government, it cannot combat the laziness of the people itself. (We need only look at the voter turnout in most modern democracies to have an idea of how low the likelihood that every citizen would show up to deliberate on matters of state in a large assembly.) The survival of the social contract depends to a large extent on the enthusiasm of the people with regard to this contract. Those who have no interest in exercising their civil freedom are guaranteed to lose it, according to Rousseau.
Looking at Rousseau's hated terms—"representation" and "finance"—will help us understand what is lost when people do not exercise popular sovereignty as a group. The first temptation, representation, undermines Rousseau's concept of fraternity. The general will can only be expressed by the people as a whole, and they cannot elect representatives to express this will for them. If the sovereign is represented it ceases to be the sovereign.
The temptation toward finance undermines Rousseau's concept of equality. If those with enough money can buy their way out of service to the state, the state itself can ultimately be bought. We might find something similar in modern democracies, where hefty campaign contributions from wealthy interest groups and politically biased journalism can do a great deal to sway an election.
When the people undermine equality and fraternity, liberty will not be able to stand alone. If we recall, Rousseau believes that people can find civil freedom only by entering into the social contract and exercising popular sovereignty. If people try to buy their way out of their duty to the state, they are essentially buying their enslavement. They will no longer have a voice in how the state is run, and they will become the slaves of those in charge.
This claim might seem a bit outlandish: most of us who live in modern representative democracies are not "slaves" to the government. However, Rousseau would suggest that we lack the initiative and agency we would have if we lived in a true republic. In the modern world, we may lack a certain degree of agency from falling too much under the sway of consumer culture. While "representation" may not inhibit our freedom too much, we might say that "finance" has enslaved us to an extent that Rousseau could not have imagined.