[GAIUS libro undecimo ad edictum prouinciale. ] §24.1.6.prquia quod ex non concessa donatione retinetur, id aut sine causa aut ex iniusta causa retineri intellegitur: ex quibus causis condictio nasci solet.
[GAIUS in the eleventh book on the Provincial Edict.] because that which is retained from a non-permitted donation is understood to be retained either without cause or from an unjust cause, from which causes a condictio is accustomed to arise.