Book 3, Chapter 17: The Institution of Government explained simply

CHAPTER XVII THE INSTITUTION OF GOVERNMENT Under what general idea then should the act by which government is instituted be conceived as falling? I will begin by stating that the act is complex, as being composed of two others--the establishment' of the law and its execution. By the former, the Sovereign decrees that there shall be a governing body established in this or that form; this act is clearly a law. By the latter, the people nominates the rulers who are to be entrusted with the government that has been established. This nomination, being a particular act, is clearly not a second law, but merely a consequence of the first and a function of government. The difficulty is to understand how there can be a governmental act before government exists, and how the people, which is only Sovereign or subject, can, under certain circumstances, become a prince or magistrate. It is at this point that there is revealed one of the astonishing properties of the body politic, by means of which it reconciles apparently contradictory operations; for this is accomplished by a sudden conversion of Sovereignty into democracy, so that, without sensible change, and merely by virtue of a new relation of all to all, the citizens become magistrates and pass from general to particular acts, from legislation to the execution of the law. This changed relation is no speculative subtlety without instances in practice: it happens every day in the English Parliament, where, on certain occasions, the Lower House resolves itself into Grand Committee, for the better discussion of affairs, and thus, from being at one moment a sovereign court, becomes at the next a mere commission; so that subsequently it reports to itself, as House of Commons, the result of its proceedings in Grand Committee, and debates over again under one name what it has already settled under another. It is, indeed, the peculiar advantage of democratic government that it can be established in actuality by a simple act of the general will. Subsequently, this provisional government remains in power, if this form is adopted, or else establishes in the name of the Sovereign the government that is prescribed by law; and thus the whole proceeding is regular. It is impossible to set up government in any other manner legitimately and in accordance with the principles so far laid down.