Aristotle, Nicomachean Ethics
H. Rackham, Ed.

We have now stated what Justice and Injustice are in principle. From the definition given, it is plain that just conduct is a mean between doing and suffering injustice, for the former is to have too much and the latter to have too little. And Justice is a mode of observing the mean, though not in the same way as the other virtues are, but because it is related to a mean, while Injustice is related to the extremes. Also, Justice is that quality in virtue of which a man is said to be disposed to do by deliberate choice that which is just, and, when distributing things between himself and another, or between two others, not to give too much to himself and too little to his neighbor of what is desirable, and too little to himself and too much to his neighbor of what is harmful, but to each what is proportionately equal; and similarly when he is distributing between two other persons.