Neither Ancient Law nor any other source of evidence discloses to us society entirely destitute of the conception of Contract. But the conception， when it first shows itself， is obviously rudimentary. No trustworthy primitive record can be read without perceiving that the habit of mind which induces us to make good a promise is as yet imperfectly developed， and that acts of flagrant perfidy are often mentioned without blame and sometimes described with approbation. In the Homeric literature， for instance， the deceitful cunning of Ulysses appears as a virtue of the same rank with the prudence of Nestor， the constancy of Hector， and the gallantry of Achilles. Ancient law is still more suggestive of the distance which separates the crude form of Contract from its maturity. At first， nothing is seen like the interposition of law to compel the performance of a promise. That which the law arms with its sanctions is not a promise， but a promise accompanied with a solemn ceremonial. Not only are formalities of equal importance with the promise itself， but they are， if anything， of greater importance； for that delicate analysis which mature jurisprudence applies to the conditions of mind under which a particular verbal assent is given appears， in ancient law， to be transferred to the words and gestures of the accompanying performance. No pledge is enforced if a single form be omitted or misplaced， but， on the other hand， if the forms can be shown to have been accurately proceeded with， it is of no avail to plead that the promise was made under duress or deception. The transmutation of this ancient view into the familiar notion of a Contract is plainly seen in the history of jurisprudence. First one or two steps in the ceremonial are dispensed with； then the others are simplified or permitted to be neglected on certain conditions； lastly， a few specific contracts are separated from the rest and allowed to be entered into without form， the selected contracts being those on which the activity and energy of social intercourse depends. Slowly， but most distinctly， the mental engagement isolates itself amid the technicalities， and gradually becomes the sole ingredient on which the interest of the jurisconsult is concentrated. Such a mental engagement， signified through external acts， the Romans called a Pact or Convention； and when the Convention has once been conceived as the nucleus of a Contract， it soon becomes the tendency of advancing jurisprudence to break away the external shell of form and ceremony. Forms are thenceforward only retained so far as they are guarantees of authenticity， and securities for caution and deliberation. The idea of a Contract is fully developed， or， to employ the Roman phrase， Contracts are absorbed in Pacts.

　　The history of this course of change in Roman law is exceedingly instructive. At the earliest dawn of the jurisprudence， the term in use for a Contract was one which is very familiar to the students of historical Latinity. It was nexum， and the parties to the contract were said to be nexi， expressions which must be carefully attended to on account of the singular durableness of the metaphor on which they are founded. The notion that persons under a contractual engagement are connected together by a strong bond or chain， continued till the last to influence the Roman jurisprudence of Contract； and flowing thence it has mixed itself with modern ideas. What then was involved in this nexum or bond？ A definition which has descended to us from one of the Latin antiquarians describes nexum as omne quod geritur per aes et libram， “every transaction with the copper and the balance，” and these words have occasioned a good deal of perplexity. The copper and the balance are the well-known accompaniments of the Mancipation， the ancient solemnity described in a former chapter， by which the right of ownership in the highest form of Roman Property was transferred from one person to another. Mancipation was a conveyance， and hence has arisen the difficulty， for the definition thus cited appears to confound Contracts and Conveyances， which in the philosophy of jurisprudence are not simply kept apart， but are actually opposed to each other. The jus in re， right in rem， right “availing against all the world，” or Proprietary Right， is sharply distinguished by the analyst of mature jurisprudence from the jus ad rem， right in personam， right “availing a single individual or group，” or obligation. Now Conveyances transfer Proprietary Rights， Contracts create Obligations —— how then can the two be included under the same name or same general conception？ This， like many similar embarrassments， has been occasioned by the error of ascribing to the mental condition of an unformed society a faculty which pre-eminently belongs to an advanced stage of intellectual development， the faculty of distinguishing in speculation ideas which are blended in practice. We have indications not to be mistaken of a state of social affairs in which Conveyances and Contracts were practically confounded； nor did the discrepance of the conceptions become perceptible till men had begun to adopt a distinct practice in contracting and conveying.

　　It may here be observed that we know enough of ancient Roman law to give some idea of the mode of transformation followed by legal conceptions and by legal phraseology in the infancy of Jurisprudence. The change which they undergo appear to be a change from general to special； or， as we might otherwise express it， the ancient conceptions and the ancient terms are subjected to a process of gradual specialisation. An ancient legal conception corresponds not to one but to several modern conceptions. An ancient technical expression serves to indicate a variety of things which in modern law have separate names allotted to them. If however we take up the history of Jurisprudence at the next stage， we find that the subordinate conceptions have gradually disengaged themselves and that the old general names are giving way to special appellations. The old general conception is not obliterated， but it has ceased to cover more than one or a few of the notions which it first included. So too the old technical name remains， but it discharges only one of the functions which it once performed. We may exemplify this phenomenon in various ways. Patriarchal Power of all sorts appears， for instance， to have been once conceived as identical in character， and it was doubtless distinguished by one name. The Power exercised by the ancestor was the same whether it was exercised over the family or the material property —— over flocks， herds， slaves， children， or wife. We cannot be absolutely certain of its old Roman name， but there is very strong reason for believing， from the number of expressions indicating shades of the notion of power into which the word manus enter， that the ancient general term was manus. But， when Roman law has advanced a little， both the name and the idea have become specialised. Power is discriminated， both in word and in conception， according to the object over which it is exerted. Exercised over material commodities or slaves， it has become dominium —— over children， it is Potestas —— over free persons whose services have been made away to another by their own ancestor， it is mancipium —— over a wife， it is still manus. The old word， it will be perceived， has not altogether fallen into desuetude， but is confined to one very special exercise of the authority it had formerly denoted. This example will enable us to comprehend the nature of the historical alliance between Contracts and Conveyances. There seems to have been one solemn ceremonial at first for all solemn transactions， and its name at Rome appears to have been nexum. Precisely the same forms which were in use when a conveyance of property was effected seem to have been employed in the making of a contract. But we have not very far to move onwards before we come to a period at which the notion of a Contract has disengaged itself from the notion of a Conveyance. A double change has thus taken place. The transaction “with the copper and the balance，” when intended to have for its office the transfer of property， is known by the new and special name of Mancipation. The ancient Nexum still designates the same ceremony， but only when it is employed for the special purpose of solemnising a contract.

　　When two or three legal conceptions are spoken of as anciently blended in one， it is not intended to imply that some one of the included notions may not be older than the others， or， when those other have been formed， may not greatly predominate over and take precedence over them. The reason why one legal conception continues so long to cover several conceptions， and one technical phrase to do instead of several， is doubtless that practical changes are accomplished in the law of primitive societies long before men see occasion to notice or name them. Though I have said that Patriarchal Power was not at first distinguished according to the objects over which it was exercised， I feel sure that Power over Children was the root of the old conception of Power； and I cannot doubt that the earliest use of the Nexum， and the one primarily regarded by those who resorted to it， was to give proper solemnity to the alienation of property. It is likely that a very slight perversion of the Nexum from its original functions first gave rise to its employment in Contracts， and that the very slightness of the change long prevented its being appreciated or noticed. The old name remained because men had not become conscious that they wanted a new one； the old notion clung to the mind because nobody had seen reason to be at the pains of examining it. We have had the process clearly exemplified in the history of Testaments. A Will was at first a simple conveyance of property. It was only the enormous practical difference that gradually showed itself between this particular conveyance and all others which caused it to be regarded separately， and even as it was， centuries elapsed before the ameliorators of law cleared away the useless encumbrance of the nominal mancipation， and consented to care for nothing in the Will but the expressed intentions of the Testator. It is unfortunate that we cannot track the early history of Contracts with the same absolute confidence as the early history of Wills， but we are not quite without hints that contracts first showed themselves through the nexum being put to a new use and afterwards obtained recognition as distinct transactions through the important practical consequences of the experiment. There is some， but not very violent， conjecture in the following delineation of the process. Let us conceive a sale for ready money as the normal type of the Nexum. The seller brought the property of which he intended to dispose —— a slave， for example —— the purchaser attended with the rough ingots of copper which served for money and an indispensable assistant， the libripens， presented himself with a pair of scales. The slave with certain fixed formalities was handed over to the vendee —— the copper was weighed by the libripens and passed to the vendor. So long as the business lasted it was a nexum， and the parties were nexi； but the moment it was completed， the nexum ended， and the vendor and purchaser ceased to bear the name derived from their momentary relation. But now， let us move a step onward in commercial history. Suppose the slave transferred， but the money not paid. In that case， the nexum is finished， so far as the seller is concerned， and when he has once handed over his property， he is no longer nexus； but， in regard to the purchaser， the nexum continues. The transaction， as to his part of it， is incomplete， and he is still considered to be nexus. It follows， therefore， that the same term described the Conveyance by which the right of property was transmitted， and the personal obligation of the debtor for the unpaid purchase-money. We may still go forward， and picture to ourselves a proceeding wholly formal， in which nothing is handed over and nothing paid； we are brought at once to a transaction indicative of much higher commercial activity， an executory Contract of Sale.

　　If it be true that， both in the popular and in the professional view， a Contract was long regarded as an incomplete Conveyance， the truth has importance for many reasons. The speculations of the last century concerning mankind in a state of nature， are not unfairly summed up in the doctrine that “in the primitive society property was nothing， and obligation everything；” and it will now be seen that， if the proposition were revered， it would be nearer the reality. On the other hand， considered historically the primitive association of Conveyances and Contracts explains something which often strikes the scholar and jurist as singularly enigmatical， I mean the extraordinary and uniform severity of very ancient systems of law to debtors， and the extravagant powers which they lodge with creditors. When once we understand that the nexum was artificially prolonged to give time to the debtor， we can better comprehend his position in the eye of the public and of the law. His indebtedness was doubtless regarded as an anomaly， and suspense of payment in general as an artifice and a distortion of strict rule. The person who had duly consummated his part in the transaction must， on the contrary， have stood in peculiar favour； and nothing would seem more natural than to arm him with stringent facilities for enfording the completion of a proceeding which， of strict right， ought never to have been extended or deferred.

　　Nexum，therefore，which originally signified a Conveyance of property， came insensibly to denote a Contract also， and ultimately so constant became the association between this word and the notion of a Contract， that a special term， Mancipium or Mancipatio， had to be used for the purpose of designating the true nexum or transaction in which the property was really transferred. Contracts are therefore now severed from Conveyances， and the first stage in their history is accomplished， but still they are far enough from that epoch of their development when the promise of the contractor has a higher sacredness than the formalities with which it is coupled. In attempting to indicate the character of the changes passed through in this interval， it is necessary to trespass a little on a subject which lies properly beyond the range of these pages， the analysis of Agreement effected by the Roman jurisconsults. Of this analysis， the most beautiful monument of their sagacity， I need not say more than that it is based on the theoretical separation of the Obligation from the Convention or Pact. Bentham and Mr. Austin have laid down that the “two main essentials of a contract are these： first， a signification by the promising party of his intention to do the acts or to observe the forbearances which he promises to do or to observe. Secondly， a signification by the promisee that he expects the promising party will fulfil the proffered promise.” This is virtually identical with the doctrine of the Roman lawyers， but then， in their view， the result of these “significations” was not a Contract， but a Convention or Pact. A Pact was the utmost product of the engagements of individuals agreeing among themselves， and it distinctly fell short of a Contract. Whether it ultimately became a Contract depended on the question whether the law annexed an Obligation to it. A Contract was a Pact （or Convention） plus an Obligation. So long as the Pact remained unclothed with the Obligation， it was called nude or naked.

　　What was an Obligation？ It is defined by the Roman lawyers as “Juris vinculum， quo necessitate adstringimur alicujus solvendae rei.” This definition connects the Obligation with the Nexum through the common metaphor on which they are founded， and shows us with much clearness the pedigree of a peculiar conception. The Obligation is the “bond” or “chain” with which the law joins together persons or groups of persons， in consequence of certain voluntary acts. The acts which have the effect of attracting an Obligation are chiefly those classed under the heads of Contract and Delict， of Agreement and Wrong； but a variety of other acts have a similar consequence which are not capable of being comprised in an exact classification. It is to be remarked， however， that the act does not draw to itself the Obligation in consequence of any moral necessity，。 it is the law which annexes it in the plenitude of its power， a point the more necessary to be noted， because a different doctrine has sometimes been propounded by modern interpreters of the Civil Law who had moral or metaphysical theories of their own to support. The image of a vinculum juris colours and pervades every part of the Roman law of Contract and Delict. The law bound the parties together， and the chain could only be undone by the process called solutio， an expression s