The Republic by Plato Part 4 Page 82

Yes, certainly.

And the division of labour which required the carpenter and the shoemaker and the rest of the citizens to be doing each his own business, and not another’s, was a shadow of justice, and for that reason it was of use?

Clearly.

But in reality justice was such as we were describing, being concerned however, not with the outward man, but with the inward, which is the true self and concernment of man: for the just man does not permit the several elements within him to interfere with one another, or any of them to do the work of others, — he sets in order his own inner life, and is his own master and his own law, and at peace with himself; and when he has bound together the three principles within him, which may be compared to the