1 The leading division of obligations is into two kinds, civil and praetorian. Those obligations are civil which are established by statute, or at least are sanctioned by the civil law; those are praetorian which the praetor has established by his own jurisdiction, and which are also called honorary. 2 By another division they are arranged in four classes, contractual, quasicontractual, delictal, and quasidelictal. And first, we must examine those which are contractual, and which again fall into four species, for contract is concluded either by delivery, by a form of words, by writing, or by consent: each of which we will treat in detail. TITLE XIV. OF REAL CONTRACTS, OR THE MODES IN WHICH OBLIGATIONS ARE CONTRACTED BY DELIVERY Real contracts, or contracts concluded by delivery, are exemplified by loan for consumption, that is to say, loan of such things as are estimated by weight, number, or measure, for instance, wine, oil, corn, coined money, copper, silver, or gold: things in which we transfer our property on condition that the receiver shall transfer to us, at a future time, not the same things, but other things of the same kind and quality: and this contract is called mutuum, because thereby meum or mine becomes tuum or thine. The action to which it gives rise is called a condiction. 1 Again, a man is bound by a real obligation if he takes what is not owed him from another who pays him by mistake; and the latter can, as plaintiff, bring a condiction against him for its recovery, after the analogy of the action whose formula ran 'if it be proved that he ought to convey,' exactly as if the defendant had received a loan from him. Consequently a pupil who, by mistake, is paid something which is not really owed him without his guardian's authority, will no more be bound by a condiction for the recovery of money not owed than by one for money received as a loan: though this kind of liability does not seem to be founded on contract; for a payment made in order to discharge a debt is intended to extinguish, not to create, an obligation.