[ULPIANUS libro quinto decimo ad edictum. ] §41.10.1.prPro suo possessio talis est.
[ULPIAN, from his fifteenth book on the Edict.] Possession "as one's own" is of the following nature.
cum dominium nobis adquiri putamus, et ex ea causa possidemus, ex qua adquiritur, et praeterea pro suo: ut puta ex causa emptionis et pro emptore et pro suo possideo, item donata uel legata uel pro donato uel pro legato etiam pro suo possideo.
It occurs when we think that ownership is acquired by us, and we possess on that ground from which ownership is acquired, and moreover "as one's own": for example, I possess on the ground of purchase both as a purchaser and as my own, and likewise I possess things given or bequeathed both as given or as bequeathed and also as my own.
§41.10.1.1Sed si res mihi ex causa iusta puta emptionis tradita sit et usucapiam, incipio quidem et ante usucapionem pro meo possidere.
But if a thing has been delivered to me on a just ground, for example, of purchase, and I acquire it by usucapion, I certainly begin to possess it as my own even before the usucapion.
sed an desinam ex causa emptionis post usucapionem, dubitatur: et Mauricianus dicitur existimasse non desinere.
But whether I cease to possess on the ground of purchase after the usucapion is doubted; and Mauricianus is said to have thought that one does not cease.