The essence and union of the society consisting in having one will, the legislative, when once established by the majority, has the declaring and, as it were, keeping of that will.
Gist of Idea
A single will creates the legislature, which is duty-bound to preserve that will
John Locke (Second Treatise of Government , 212)
Not far from Rousseau's big idea, apart from the emphasis on the 'majority'. Rousseau reduced the role of the general will to preliminaries and basics, but wanted close to unanimity, so that everyone accepts being a subject, to government and law.
Locke,John: 'Two Treatises of Government' [Everyman 1988], p.225