What are the two reasons that Machiavelli gives for his opinion that the courts (Faculty of Accusing) are the most necessary and useful authority to guard liberty in a City?

The two reasons that Machiavelli gives for his opinion that courts are most necessary and useful to guard liberty in a city. This is because people will not attempt to do anything against the state out of fear of immediate punishment, and courts provide a vent to those moods which may arise in a City.