at the proper time, the donor dies or loses his mind without making a charter and  the donee subsequently secures a charter of gift; the gift will be good [and], though  the seal is genuine, the charter void. On this matter more is said below.1
That a gift is invalid unless livery follows. Of the kinds of possession and how the possession of things is acquired.
 As we have said above, some gifts are complete, others incomplete. Since to give is  to make the thing the property of the donee,2 a gift will never be complete until  the donee has full possession or seisin, [by himself alone, with no other who claims  a right in the thing,] that is, until the thing has been delivered to him, for by  liveries and usucapions possessions and the dominion of things are transferred,3 for  it does not suffice if the right is granted to another unless the donee obtains seisin.  But since possession or seisin is of many kinds, we must first see what possession is  and into what divisions it falls. [Also how it is acquired, by livery or in some other  way,4 and by what persons;5 and how, when acquired, it is retained;6 and how one  must use it,7 and if [a gift] is made to several, who shall be preferred,8 [then] how,  once acquired, it may be lost,9 and when lost, how recovered.]
What possession is.
 What is possession? It is clear that 10possession is the detention corpore and animo  of a corporeal thing, with the concurrent support of right. Of a corporeal thing,  it is said, because incorporeal things cannot be possessed or be the subjects of  usucapion or be transferred apart from some corporeal thing, since they do not  admit of livery by themselves. They therefore are said to be quasi-possessed [and]  can be transferred or quasi-transferred by acquiescence and use.11 Possession is also  said to be the detention of a thing, because it is held naturally by him who has  it, that is, physically,12 With respect to what is said, corpore and animo with the  concurrent support of right,13 more will be said below.1415When one is in possession  and we dispute it against him, the dispute involves either that there be restored  to us what is ours but we do not possess, [as where we have been wrongfully ejected  from our own possession, or another's, as that of our ancestors,] or that (by  interdict) we be allowed
15-16. D. 18.104.22.168: omnis de possessione controversia aut eo pertinet ut quod non possidemus nobis restituatur aut ad hoc, ut retinere nobis liceat quod possidemus. Restitutae possessionis ordo aut interdicto expeditur aut per actionem, retinendae itaque possessionis duplex via est, aut exceptio aut interdictum. Exceptio datur ex multis causis ...; infra 294