Here we find the following key ideas of government:
Suffrage should be given and limited to the right people. For this is precisely choosing a sovereign.
The people should decide everything they can decide. What they can't decide, because of its complexity or its need for quick decision ("the motion of the people [being] always either too remiss or too violent."), should be decided by the representatives of the people Therefore, these representatives should be chosen by the people. The people are quite able to select representatives using common sense (see quote below.)
Suffrage should be public so that the upper classes can influence the vote of the lower who otherwise might vote for their own destruction.
Montesquieu says that "[t]he people are extremely well qualified for choosing those whom they are to intrust with part of their authority," because the facts required for them to do so (for example who has been a good general and who is talented in business) are obvious. However, he warns that when they "are gained by bribery and corruption," they "grow indifferent to public affairs and avarice becomes their predominant passion. Unconcerned about the government and everything belonging to it, they quietly wait for their hire."
