Rabash, Shlavey Hasulam (Steps of the Ladder), “Judges and Guards”: It is said: “You should post judges and guards at all your gates.” When a person wants to start the work of the Creator, he goes through two stages:
1. Theory. He first makes himself a plan: what he should do and what he shouldn’t. That is, this is the clarification of good and evil, and this theoretical part is called a “judge” who tells him what to do.
2. Then he has to put theory into practice, and it is already called a “guard.”
It isn’t a single day’s work, but one has to exert himself in the work daily. Therefore, the plural form is used: “judges and guards.”
From the 4th part of the Daily Kabbalah Lesson 2/19/12, “Advice for the Arava Convention”