The Institutes tell us that all men are either slaves or free, and both liberty and slavery are defined by Justinian in terms borrowed from Florentinus. “ Libertas,” he tells us, “ est naturalis facultas eius quod cuique facere libet nisi si quid vi aut iure prohibetur.” No one has defined liberty well: of this definition, which, literally understood, would make everyone free, the only thing to be said at present for our purpose is that it assumes a state of liberty to be “ natural.”

” Servitus,” he says, “ est constitutio iuris gentium qua quis dominio alieno contra naturam subicitur.” Upon this definition two remarks may be made.

i. Slavery is the only case in which, in the extant sources of Roman law, a conflict is declared to exist between the Ius Gentium. and the Ius Naturale. It is of course inconsistent with that universal equality of man which Roman speculations on the Law of Nature assume, and we are repeatedly told that it is a part of the Ius Gentium, since it originates in war. Captives, it is said, may be slain: to make them slaves is to save their lives; hence they are called send, ut servati, and thus both names, serous and mancipium, are derived from capture in war.