[POMPONIUS libro quinto decimo ad Sabinum. ] §33.2.6.prSi usus fructus mihi in biennium continuum a morte testatoris legatus sit et per heredem steterit, quo minus eum mihi daret, praeterito biennio nihilo minus tenetur (quemadmodum teneretur, si res legata in rerum natura esse desisset, quam quis deberet, moratusque esset in ea danda), ut peti quidem iam usus fructus qui legatus sit non possit, quia alius futurus sit quam qui legatus fuerit, sed aestimatio eius bima dumtaxat facienda sit.
[POMPONIUS, On Sabinus, book XV.] If a usufruct for a continuous period of two years from the death of the testator has been bequeathed to me, and it has been due to the heir that he did not grant it to me, the heir is nonetheless liable after the two years have elapsed (just as he would be liable if the bequeathed thing, which someone owed, had ceased to exist in the nature of things, and he had been in default in giving it), with the result that, although the usufruct which was bequeathed can indeed no longer be claimed—because any future usufruct would be different from the one that was bequeathed—nevertheless, an assessment of its value for those two years must at least be made.