But to govern ill is disadvantageous to both; for the same thing is useful to the part and to the whole, to the body and to the soul; but the slave is as it were a part of the master, as if he were an animated part of his body, though separate.

For which reason a mutual utility and friendship may subsist between the master and the slave, I mean when they are placed by nature in that relation to each other, for the contrary takes place amongst those who are reduced to slavery by the law, or by conquest..