That fault creates the obligation to make good the loss

We have said above that there are three sources of our legal claims: pact, wrong, and statute. Enough has been said about contracts. Let us come now to what is due by the law of nature in consequence of a wrong. By a wrong (maleficium), we here mean every fault (culpa), whether of commission or of omission, which is in conflict with what men ought to do, either from their common interest or by reason of a special quality. From such a fault, if damage has been caused, [then] by the law of nature an obligation arises, namely, that the damage should be made good.

Damage as that which conflicts with one's right taken in a strict sense

Damage [occurs]…when anyone has less than belongs to him, whether by a right that accrues to him from the law of nature alone, or [one that] is reinforced by the addition of a human act, as by ownership, contract, or legal enactment. By nature, a man's life is his own, not indeed to destroy, but to safeguard; also his own are his body, limbs, reputation, honour, and the acts of his will. The previous part of our treatise has shown how each man, by property right and by agreements, possesses his own not only with respect to property but also with respect to the acts of others. In a similar manner, everyone acquires his particular rights from the law, because the law has the same power, or greater power, that individuals have over themselves or their property. Thus a ward has the right to demand a certain degree of diligence and care from his guardian, and likewise the state from an official; and not the state only, but also individual citizens, as often as the law indicates such a requirement explicitly, or by a sufficiently clear implication.