The Republic by Plato Part 2 Page 36

I will tell you, I replied; justice, which is the subject of our enquiry, is, as you know, sometimes spoken of as the virtue of an individual, and sometimes as the virtue of a State.

True, he replied.

And is not a State larger than an individual?

It is.

Then in the larger the quantity of justice is likely to be larger and more easily discernible. I propose therefore that we enquire into the nature of justice and injustice, first as they appear in the State, and secondly in the individual, proceeding from the greater to the lesser and comparing them.

That, he said, is an excellent proposal.

And if we imagine the State in process of creation, we shall