According to Skinner, a key text on slavery is in Justinian's Digest: "There we learn that slavery can be defined as 'an institution of the ius gentium by which someone is, contrary to nature, subjected to the dominion of someone else.'" From this definition, Skinner proceeds, "it follows that what it means for someone to lack the status of a free subject must be for that person not to be sui iuris but instead to be
sub potestate, under the power or subject to the will of someone else (Quentin Skinner, "Classical liberty, Renaissance translation and the English civil war," in Visions of Politics, Vol.