Full Idea
We call 'just' anything that tends to produce or conserve the happiness of a political association.
Gist of Idea
Justice is whatever creates or preserves social happiness
Source
Aristotle (Nicomachean Ethics [c.334 BCE], 1129b18)
Book Reference
Aristotle: 'Ethics (Nicomachean)', ed/tr. ThomsonJ A K/TredennickH [Penguin 1976], p.173
A Reaction
This is closer to a modern view, though we probably think that some societies might flourish while being unjust, while others might be very just but disintegrate. We are more cynical than Aristotle.