The general will is always right. ....There is often a great deal of difference between the will of all and the general will. The latter considers only the general interest, but the former considers private interest and is merely the sum of private wills.
Gist of Idea
The general will is always right, but the will of all can err, because it includes private interests
Jean-Jacques Rousseau (The Social Contract (tr Cress) , II.03)
Hence in order to get an expression of the general will, voters must exclusively focus on the general good. I do that in general elections, only to find that the people around me vote for their own interests. I wish we all did the same thing.
Rousseau,Jean-Jacques: 'The Basic Political Writings', ed/tr. Cress,Donald A. [Hackett 1987], p.155