How the dominion of things is acquired by the jus naturale or the jus gentium.
 1We have treated above of the classification of things. 2Now we must explain how  the dominion of things is acquired according to natural law or the jus gentium (to  start first with the older law, which, with the human race itself, proceeded from  the nature of things) and then how it is acquired according to the civil law,3 which  came into existence later, after states came to be founded, magistrates created  and laws reduced to writing.4
Of wild beasts.
 5By the jus gentium or natural law the dominion of things is acquired in many  ways. First by taking possession of things that are owned by no one,6[and do [not]  now belong to the king by the civil law,7 no longer being common as before,]89as  wild beasts, birds and fish, that is, all the creatures born on the earth, in the sea  or in the heavens, that is, in the air, no matter where they may be taken. When  they are captured they begin to be mine, because they are forcibly kept in my  custody, and by the same token, if they escape from it and recover their natural  liberty they cease to be mine and are again made the property of the taker. They  recover their natural liberty when they escape from my sight into the free air and  are no longer in my keeping, or when, though still within my view, their pursuit is  no longer possible.10
Of fishing, hunting, and capture.
 11The taking of possession also includes fishing, hunting and capture. It is not  pursuit alone that makes a thing mine, for though I have wounded a wild beast  so severely that it may be captured, it nevertheless is not mine unless I capture it;  rather it will belong to the one who next takes it, for much may happen to prevent  my capture of it. And so if a wild boar falls into a net you have set, and though  he is caught fast in it I have extricated him and carried him off; he will be mine  if he comes into my power, unless custom rules to the contrary12 or [the king's]  privilege.