Liberty. Who is Free?

What is Liberty or Freedom? Who is free? The Civilized Man, the Savage, or the Millionaire?... It might seem that liberty was one of the most trite and worn of all subjects. It will be the aim of this essay to show that liberty is the least well analyzed of all the important social conceptions, that it is the thing at stake in the most important current controversies, and that it needs to be defended as much against those who abuse it as against those who deride it.
The history of the dogma of the natural liberty of all men, with the cognate dogma of the natural equality of all men, would be an important topic for exhaustive treatment by itself. From the notes which I have made on the subject I condense as far as possible the following view of it. Slavery in the classical states seems to have rested upon the law of war, that the vanquished man with his family and all his property fell under the good pleasure of the conqueror.
Xenophon states this law explicitly: "The law is well known among all men that, when a state goes to war, the property and bodies of all in the state are the property of the captors. You will, therefore, not possess wrongfully whatever you get, but, if you permit them to retain anything, it will be out of humanity."