The Republic by Plato Part 4 Page 47

Because I think that this is the only virtue which remains in the State when the other virtues of temperance and courage and wisdom are abstracted; and, that this is the ultimate cause and condition of the existence of all of them, and while remaining in them is also their preservative; and we were saying that if the three were discovered by us, justice would be the fourth or remaining one.

That follows of necessity.

If we are asked to determine which of these four qualities by its presence contributes most to the excellence of the State, whether the agreement of rulers and subjects, or the preservation in the soldiers of the opinion which the law ordains about the true nature of dangers, or wisdom and watchfulness in the rulers, or whether this other which I am mentioning, and which is