Chapter — Billuart, Summa Summae · from Schola Thomistica
On the Ways of Acquiring Ownership
Things, with respect to dominion, are of two kinds. Some are appropriated, that is, they have a proper and determinate dominion. Some are common or quasi-common, namely such as are held to have no lord of themselves, as are wild beasts in the forests, fish in the rivers, etc. And in accordance with this diversity of things, the ways of acquiring their dominions are diverse. Of things that are appropriated to someone, dominion is acquired by the will of the lord or by the authority of the law. Of things that belong to no one, dominion is acquired by first occupation.
Res respective ad dominium sunt duplicis generis. Quaedam sunt appropriatae, id est, habent proprium et determinatum dominium. Quaedam sunt communes aut quasi communes, quae scilicet nullum ex se censentur habere dominum, ut sunt ferae in silvis, pisces in fluviis, etc. Et iuxta hanc rerum diversitatem diversi sunt modi earum dominia acquirendi. Harum quae sunt alicui appropriatae acquiritur dominium voluntate domini vel authoritate legis. Illarum quae nullius sunt, acquiritur dominium prima occupatione.