ESTABLISHMENT. Obligations, as regards their origin. were divided by the Roman jurists into four classes: (1) those established by contract (ex contract:) ; (2) those established by tort of the debtor ('x delictol ; (3) those which re semble contractual obligation. although no con tract has been concluded (quasi cx contracta); and (4) those which resemble obligations on tort, although the debtor himself has committed no tort (quasi cx (Nieto). The most important quasi-contractual obligations are those based on unjust enrichment and those which spring from unauthorized agency. The quasi-tortious obliga tions include all the cases in which a person (father, employer, etc.) is held liable for a tort which he did not commit or authorize. The clas sification is open to criticism, and while modern civil codes recognize obligations of the third and fourth class, they are sometimes described as imposed by law.' This description is also open to criticism, as implying that con tractual obligations are not imposed by law. In the new German code all attempt at classifi cation is abandoned. except that contractual obli gations and quasi-contractual obligations are thrown together, and that all cases of liability for illicit conduct are placed under a separate title.
ExrINCTION. Obligations are normally extin guished by performance. If the creditor sees fit to accept as performance something other or something less than he is entitled to demand, the obligation is extinguished. Tender of perform ance does not have the same effect ; hut if the obligation is to pay a sum of money or to deliver goods. the debtor is liberated by depositing the money or goods in a safe place subject to the creditor's order. Obligations are also extinguished
by the substitution of new obligations tion), if such was the intention of the parties. Obligations are likewise extinguished by merger (confusion) when the claim and the debt are united in the same person (e.g. by inheritance) : by set-off (compensation) when a debtor, being sued. is able to put in a counterclaim: by re lease; and by discharge in bankruptcy proceed ings.
OftmoArtox. The Roman jurists sometimes used the term natural obligation to mean an obligation recognized by natural law (q.v.), thus including the majority of legal obligations. Alore technically, however. they employed the term to describe an obligation which was legally imperfect, and which could not lie enforced by action at law. but which a scrupu lous man would recognize and perform. To all such natural obligations they attributed at least this effect, that voluntary performance was to he regarded as performance and not as gift. Fur titer, money paid or property transferred under• the mistaken impression that a legal obligation existed ettuld not be n-covercd if a natural obli gation existed. In many eases. moreover, a mi ni-al obligation was a sufficient basis for surety ship or for a nett• promise, and in a eases such an obligation could lie used as a set-ufl• against a legal obligation. Modern legislators do not regard the conception w•itlt favor, hut the courts have not been able to dispense with it. Consult the authorities referred to under Civil, 1..t w-.