Digestorum libri
Ex libro XVII
Ad Dig. 22,3,12ROHGE, Bd. 22 (1878), Nr. 66, S. 300: Beweis fortdauernder Bereicherung.The Same, Digest, Book XVII. Fifty aurei were bequeathed to you by will, and the same legacy was included in codicils which were subsequently executed. It is important to ascertain whether the testator intended to double the legacy, or merely to repeatedly mention it, or did so, having forgotten that he had already made the bequest in his will. From which party then must proof of the intention of the testator be exacted? At first sight, it would appear more just that the plaintiff should prove what he claims, but there is no doubt that proof is sometimes required of the defendant; for if I bring suit for a claim and the defendant answers that the money has been paid, he himself is required to establish this. Therefore, in the present instance, if the plaintiff exhibits two instruments, and the heir alleges that the last one is void, the latter must prove this in court.
Celsus, Digest, Book XVII. If a testator should bequeath all his female slaves and the children born of them, and one of said slaves should die, Servius denies that her child is due, for the reason that it was bequeathed by way of accessory. I think that this opinion is incorrect, and that it is in accordance with neither the language nor the intention of the deceased.