74 HARVARD LAW REVIEW, as were created by the acts of the parties (conventional hypothe- cations) and such as were created by the act of the law (legal or tacit hypothecations). Again, so long as a change of possession was indispensable, it is plain that the obligation could attach only upon property which was perfectly identified, and that there could be no change in the property subject to the obligation, except by a new change of possession. But when a change of possession had been dispensed with, and particularly when legal or tacit hypothe- cations had been introduced, it became perfectly feasible to make the obligation attach upon all property, or all property of a cer* tain description, either then belonging to the debtor or afterward acquired by him, or upon all property, or all property of a certain description, belonging to the debtor, for the time being; and hence hypothecations came to be divided into those which were special and those which were general. Except in the particulars just stated, there was no difference be- tween the pignus and the hypotheca. Each was alike a real obli- gation ; and if, as generally happened, the debt was created by a personal obligation, the latter was the principal obligation, while the former was merely accessory, collateral, or incidental to the latter; and hence, whenever the principal obligation was extin- guished, the accessory obligation fell with it; and this explains the fact that payment of the debt extinguished the creditor's rights in the property pignorated or hypothecated to him. Moreover, if the property belonged to some other person than the debtor, the real obligation was regarded as an obligation of suretyship, the property being regarded as a real surety for the debt, just as its owner would have been a personal surety, if he had incurred a personal obligation of suretyship ; and hence the owner of the property had the same rights of subrogation, whether his property was a real surety, or he himself was a personal surety, for the debt. . If the debt was not paid when it became due, the creditor's remedy upon the real obligation against the property was closely analogous to his remedy upon the debtor's personal obligation against the debtor's body, i. e., he was entitled to proceed against the property judicially, and have it condemned and sold for the payment of the debt. The Roman law in respect to the pignus has been a part of the English law, under the name of pawn or pledge, from time imme- morial, so far as it is applicable to movable property, and it has never undergone any material change, either in England or in this
