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

For the superior words of that law demonstrate this, just as if the Jurist had said that all men are equally free. Again, it seems to stand in the way that the father is naturally bound to his son (Digest 15.1.1, § "quaesitum"), but not to himself, as we will prove below. Therefore, that obligation is not acquired for the father. I concede. But you do not correctly infer the universal from the particular if you gather from it that no obligation is acquired for the father. In this species, the father cannot be the creditor of himself. But if another were obligated, rather than the father, it would be no absurdity if we said the father becomes the creditor. Yet this objection perhaps cannot be solved by those who think that it is so acquired for the father through the son, that an obligation never subsists in the person of the son. For in this case, there is no doubt that an obligation is made in the person of the son, inasmuch as it cannot be acquired for the father. While they say, however, that in this case the obligation is acquired for the father—although meanwhile it is not understood to be acquired while the peculium is with the son—they ought to confirm their opinion by a certain law or reason, or show us why the same cannot be said when someone else is obligated to anyone.