[IDEM libro trigensimo primo ad Sabinum. ] §41.3.27.prCelsus libro trigensimo quarto errare eos ait, qui existimarent, cuius rei quisque bona fide adeptus sit possessionem, pro suo usucapere eum posse nihil referre, emerit nec ne, donatum sit nec ne, si modo emptum uel donatum sibi existimauerit, quia neque pro legato neque pro donato neque pro dote usucapio ualeat, si nulla donatio, nulla dos, nullum legatum sit.
[THE SAME, On Sabinus, book 31] Celsus, in his thirty-fourth book, says that those are in error who think that, in regard to any property of which a person has acquired possession in good faith, he can usucapt it "as his own" (pro suo), and that it makes no difference whether he bought it or not, or whether it was given to him or not, provided only he believed that it was bought by or given to him; because usucapion "as a legacy" (pro legato), "as a gift" (pro donato), or "as a dowry" (pro dote) is not valid if there is in fact no gift, no dowry, and no legacy.
idem et in litis aestimatione placet, ut, nisi uere quis litis aestimationem subierit, usucapere non possit.
The same rule is accepted also in the case of the payment of the estimated value of a lawsuit (litis aestimatio), so that unless a person has truly undergone the estimation of the lawsuit, he cannot usucapt.