Iul. Pacii Iuriscons. in L. frater à fratre D. de condictione indebiti, commentarius

For the Emperor teaches universally and without distinction that an obligation is acquired for the father (Institutes 2.9, in the opening). And the same in § 1. "Whatever," he says, "had reached the sons of families, excluding of course castrensia peculia, they acquired this for their parents without any distinction." And Ulpian in Digest 44.7.1, in the opening: "Whatever a son of a family acquires for himself, the benefit of it he seeks for the father." It appears that the legislators use general words, such as these words: "Whatever" and "whatsoever." To prove this same thing, the law "Placet" is wont to be cited (Digest 28.6.79), but wrongly. For it does not say that everything is acquired for the father through the son. It also does not say that this is acquired rather than that; but it teaches that what is sought for the father is immediately acquired. This is better proved from the fact that the peculium is said to be [calculated] after deducting that which the slave owes to the master, or to fellow slaves, or to the sons (Digest 15.1.9, § "peculium"; 15.1.6, in the opening; Institutes 4.7, § "cum autem"). For who doubts that a slave is naturally indebted to the sons? Yet this obligation is said to be acquired for the father (Digest 15.1.9, § "peculium"). But that I may not stray further, our Africanus, in the opening of this law, confirms this opinion in two places. First, when he says that money paid by a brother who borrowed from a brother after the death of the father is not recovered for the part which he, who received the loan, survived as heir. There would be no reason for this statement unless the obligation were acquired for the father; and thus, it was lifted by confusion, the debtor son succeeding to the father who was the creditor. Again, when he speaks to the son who is also the debtor. In this place, retaining the same species, he speaks of him who received a loan from a brother, and he calls the same person both son and debtor. But whose debtor does he call him? Not the brother's, but the father's. For the force of the word "the same" original: "eidem" is not nothing. And altogether, when we call a son a debtor, without adding whose son he is or whose debtor, we signify that he is the same person who is both the son and the debtor of that same [father]. Furthermore, if a civil obligation is sought for the father, then a natural one is too, which is more easily acquired through another than a civil one (Digest 41.1.53). And if a natural obligation...