The Republic by Plato Part 4 Page 52

First let us complete the old investigation, which we began, as you remember, under the impression that, if we could previously examine justice on the larger scale, there would be less difficulty in discerning her in the individual. That larger example appeared to be the State, and accordingly we constructed as good a one as we could, knowing well that in the good State justice would be found. Let the discovery which we made be now applied to the individual — if they agree, we shall be satisfied; or, if there be a difference in the individual, we will come back to the State and have another trial of the theory. The friction of the two when rubbed together may possibly strike a light in which justice will shine forth, and the vision which is then revealed we will fix in our souls.

That will be in regular course; let us do as you say.