Understanding Justice and Honor

In Book VI of the Republic, while debating with Glaucon on the type of man who should govern the city, Socrates makes a simple statement:

 

"...a man who does not understand how justice and honor are related to the good won't guard them very effectively."

 

I completely agree with this assumption. If a ruler does not know how justice and honor correlate to what is good then they cannot truly understand what "the good" is, and without that understanding they will never be able to lead their people to the ultimate city that Socrates is defending.  If a ruler does not have an understanding of justice, the city will become corrupt. If a ruler does not understand honor then he himself will become corrupt. Without these two founding principles a ruler can never know what is good, and therefore cannot defend it or the principles that amount to it.