How possession of a right not subject to livery is acquired by long use.
 We have explained how one acquires possession of a corporeal thing through lapse  of time and without livery, with use or without it. Now we must show how possession  of an incorporeal thing, as the possession of a right, that is, of a servitude, is  acquired by acquiescence which is ascribed to consent and long and peaceful use,  without any act of creation or express agreement. [From such use and acquiescence  a constitution and agreement is presumed.]1[Acquiescence is taken for consent, and  as consent may be tacit or express, so agreement may be tacit or express.] The  possession of a right is acquired by use, as where an owner, being present and cognizant  of the matter, by acquiescence permits a neighbour, who has no right to do so,  to use some servitude in his unencumbered estate (as that of pasturing cattle, a  right of passage, a right to drive beasts or of conducting water or the like) for a long  time, peacefully and without interruption,2 so that the user cannot be ejected without  writ and judgment. He being present and cognizant of the matter, I say, for  if he is absent, or present and without knowledge and would prohibit the use if he  knew of it, such use will be ineffective, since it is clandestine.3 So if it is nocturnal,  or forcible.4 So if it is a servitude at will which may be revoked in season,5 and out  since it depends solely upon the grace and favour of the grantor, as one from time  to time. [If] from term to term, as from year to year, for a service certain,6 or for an  uncertain service for a fixed term,7 [that is], provided either [the payment or] the  service is certain or8 the term, possession will be genuine and sufficient. But if the  service is uncertain, whether the term is fixed or not, as where sometimes more is  done, sometimes less, there will be a lease of herbage rather than a right of pasture.9  If in the absence of the true lord one uses with the acquiescence and permission of a  servant, or of another who has no right to grant it or to create a servitude, such use  will not suffice nor will it be good with respect to acquiring possession.10
On acquiring the dominion of incorporeal things, as rights, liberties and servitudes.
 We have shown above how the dominion of corporeal things capable of livery is  acquired through the causa of gift, and how it is then transferred from person to  person by livery, or quasi-livery,11 by mutual consent, tacit or express: tacit, which  suffices for livery because the gift is not expressly revoked though it may be; express,  [that is], by express ratification.12 Also
1. ex tali ... et voluntate, from lines 12-13; constitutione for consensu
2. Supra n. 1; om: Et ita ... ex tempore, a connective