they are free with respect to the jus naturale,1 thus free and bond, but from different  points of view, and so wholly free [or] wholly bond, not in part one and part the other,2  as was said above. And in this connexion the civil law or the jus gentium detracts  from natural law.3
What bondage is.
 4Servitude is an institution of the jus gentium, by which, contrary to nature, one  person is subjected to the dominion of another. It is called such from conserving,  not serving, for in ancient times it was the practice of princes to sell captives and  thus preserve rather than destroy them. They may also be called mancipia, because  they are taken from the enemy with the hand.5 That is why, when they are freed they  are called6 manumitti, released, so to speak, from the hand. Not every servus,  however, is so called from conserving, but from serving, [and though] from  serving, not every one who serves is a servus, as may be seen in the case of the  tabellio,78He is called a servus publicus not from conserving but from serving.9
Bondsmen are either born unfree or are made such; how they are born unfree.
 10Bondsmen are either born or made such. They are born of a villein and a neif,  married or unmarried, whether they are under the potestas of a lord or outside it.  11[If he is born of the villein of one lord and the neif of another, we must then see  in whose villeinage he was born, that we may know whose villein he ought to be.]12  He is born a bondsman who is procreated of an unmarried neif though of a free  father, for he follows the condition of his mother, as though conceived at large.  Also he who is begotten of a free father who has connexion with a neif established  in a villein tenement, whether they are married or not. Conversely, if a villein has  connexion with a free woman in a free tenement, their offspring will be [free;13 if  they are married or it is a villein tenement], bond, [for] whom the child must  follow, the father or the mother, [depends] upon whether they are married or not,14  and whether they are under the potestas of his lords or beyond it. If born of a free  man and a neif out of wedlock, the child will be a villein, for he follows the condition  of his mother, [even] if he is born outside the villein tenement, but if he is  born of such persons in wedlock, outside the villeinage and in a free bed,15 he  will be free, as though born of a free woman and a free man. And so persons are  born bond.
How men are made bond.
 16Free men are made bond by capture, by virtue of the jus gentium as was
7. Accursius, gl. on v. servare, Inst. 1.3.3: Nota servum dici a servando, non a serviendo, secundum Isidorum; sed tabellio dicitur servus publicus a serviendo (D. 1.7.18) qui tamen servus esse non potest (C. 10.69.3).