mental attitude of the contractors is solely regarded, and external circumstances have no title to notice except as evidence of the inward undertaking. It is of course uncertain how far this progress of Roman ideas from a gross to a refined conception exemplifies the necessary progress of human thought on the subject of Contract. The Contract-law of all other ancient societies but the Roman is either too scanty to furnish information, or else is entirely lost; and modern jurisprudence is so thoroughly leavened with the Roman notions that it furnishes us with no contrasts or parallels from which instruction can be gleaned. From the absence, however,. the of everything violent, marvellous, or unintelligible in changes I have described, it may be reasonably believed that the history of ancient Roman Contracts is, up to a certain point, typical of the history of this class of legal conceptions in other ancient societies. But it is only up to a certain point that the progress of Roman law can be taken to represent the progress of other systems of jurisprudence. The theory of Natural law is exclusively Roman. The notion of the vinculum juris, so far as my knowledge extends, is exclusively Roman. The many peculiarities of the mature Roman law of Contract and Delict which are traceable to these two ideas, whether singly or in combination, are therefore among the exclusive products of one particular society. These later legal
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