Let us now pass on to obligations. An obligation is a legal bond, with which we are bound by a necessity of performing some act according to the laws of our State.

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.