The development of the Roman law furnishes an interesting illustration of the principles which applied generally to the development of contracts. The earliest contracts were the formal contracts. Certain of these were contracts the form of which was religious and which were enforced primarily by a religious sanction. The religion of Rome was its own native religion and not a foreign importation. For this reason and because of the fact that the college of pontiffs, the priestly caste, were the oracles of the Roman law at the early period of its development. the religious element in Roman law persisted longer than in English law at a corresponding stage of development. The most solemn of the formal religious promissory oaths was the jus jurandnm by which the promisor devoted himself to the infernal gods in case he should break his promise; and which was enforced by penalties amounting practically to outlawry and excommunication. A less drastic form of religious promise was probably the sponsio in which the promisor poured out a libation of wine calling upon the gods to witness his promise. With the disappearance of the religious element and the substitution of the power of the state as a sanction, this turns into the formal oral stipulatio which is entered into by formal question and formal answer. A very early contract at Roman law was the nexum, the contract per aes et libram, by means of the money and the scales. The transaction took the form of a symbolic sale, before five witnesses, and the libripens, who held the official scales. A formal dialogue between promisor and promisee took place, during which the scales were struck with the piece of money, probably as a symbol of weighing the copper. The absence of any of these formalities vitiated the contract. This was a loan contract which involved the debtor in very serious consequences in case of his default. The exact nature of these consequences has always been a matter of dispute; 1 but they were sufficiently serious to form one of the great grievances of the debtor in early Rome. The contract litteris grew out of the Roman custom of keeping books of account for each of the families. An entry upon the creditors books if based upon a lawful causa operated as a contract at least if such entry were made with the consent of the debtor. The contracts which grew out of performance on one side in return for an executory obligation on the other side were known as real contracts at the Roman law. The elements of contracts of this sort were the delivery or performance by the one side, together with the mutual intention of entering into the contract. There were four of these real contracts; the mutuum which was a transfer of property to the debtor to be repaid by him in kind to the creditor; the commodatum which was the gratuitous loan, the depositum which was a transfer of property for gratuitous safekeeping; and the pignus or pledge, which was the transfer of property by the debtor to the creditor as security for the debt. At a later stage the Roman law recognized the consentual contracts which depended upon the mutual agreement of the parties. It recognized, however, only four classes of these contracts; the sale, the locatio conductio, which was divided into three classes, rei, operarum, and operis, in other words contracts for the hire of a thing for a certain time, and for a certain compensation, contracts for services generally, and contracts for a certain specific job; the societas or partnership, and the mandatum or the contract for gratuitous agency. Additions were made from time to time to these classes of contracts. Of the pacta or promises which originally were unenforceable, some were recognized, by the jus civile or the early law of Rome peculiar to Roman citizens; some were recognized and made enforceable by the edict of the praetor; and some were made enforceable by later imperial legislation. A number of real contracts which were outside of the original list of real contracts were recognized and enforced under the general heading of the innominate contracts; that is, contracts haying no definite name. In Justinian's arrangement these were grouped under the four headings do ut des, do ut facias, facio ut des, and facio ut facias. During the entire period of the development of Roman law, including the final period of codification, no general theory of contract was worked out. Many different classes of contracts were recognized; but unless a contract could be placed under one of these classes, it was one of the innumerable pacta which might operate as a defense, but which could not be enforced in an action. Modern civil law, which is Roman law applied to modern life on the continent of Europe, endeavored in vain to make the Roman classes of contract fit modern conditions; and finally it was driven to take the position that every deliberate declaration of intention which was made with the intention of creating an obligation should have that effect. This was effected by Pothier's declaration that "the principles of Roman law respecting the different kinds of agreements and the distinction between contracts and simple agreements, not being founded on the law of nature and being indeed very far from simplicity are not recognized in our law."2

1 The recent controversy about nexum by F. de Zulueta, 29 Law Quarterly

Review, 137; Buckland, Soman Private Law, pp. 233, et seq.