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quite true that any violence, even killing, which is necessary to prevent the consumation of a violent felony is justifiable; but the killing, to be justified, must be necessary for the purpose. It is necessary in the case supposed to kill to prevent robbery; but, where one murderously assailed can safely escape by retreat, killing is not necessary to prevent murder. If one not obliged to retreat can escape the necessity of killing by less serious vio lence as by disarming the assailant or by knocking him down, he must do so. Whether he must first call upon bystanders for help is not certainly determined; but it is probably not necessary as a matter of law. SIR FREDERICK POLLOCK'S recent admirable lectures "The Law of Reason" are printed in the December number of the Michigan Law Review. The subject is treated under two heads—"The Law of Nature," and "Na tural Justice in the Common Law." Speak ing of the reasonableness which is "the life of the Common Law," he shows that we owe this ideal to the Greeks, the Law of Nature, as accepted throughout the Middle Ages, being derived directly or indirectly from Greek theories of ethics. He adds: The Roman conception involved in "aequum ct bonttm" or "acquitas," is identical with what we mean by "reasonable," or very nearly so. ... The Roman lawyers, in search of a rational sanction for the authority of the jus gentium, had gone to the Greek philosophy of natural justice; the medieval publicists, twelve centuries later, found in their revived learning this fabric of natural reason claiming respect by the triple authority of Aristotle, Cicero, and the Cor pus Juris; this last, be it observed, being no pagan document, but the legislation of the orthodox emperor Justinian. Evidently the Law of Nature must have its place in the Christian system of Church and State, and no mean place. The problem was solved in the Decretum of Gratian by identifying the Law of Nature with the Law of God, as the Roman jurists had identified the jus
gentium with the Law of Nature. . . . If it be asked why common lawyers did not express ly refer to the Law of Nature, the answer is that at no time after, at latest, the Papal in terference in the English politics of the first half of the thirteenth century, was the 'cita tion of Roman canonical authority accept able in our country, save so far as it was necessary for strictly technical purposes. Besides, any such citation might have been construed as a renunciation of independence, or a submission of questions of general policy to the judgment of the Church. These considerations appear sufficient to explain why "it is not used among them that be learned in the laws of England to reason what thing is commanded or prohibited by the Law of Nature." Of Natural Justice in the Common Law he savs: The real and fruitful conquests of the principle of natural justice or reasonableness in our law belong to its modern growth. Students fresh from striving with the verbal archaism of our law-books must find it hard to realize that the nineteenth century, after the thirteenth, has been the most vital period of the Common Law. The greater part of our actual working jurisprudence was made by men born in the early years of that century, the contemporaries of Darwin and Emerson. A hundred years ago the law of contract was, to say the least, very far from complete, and the law of negligence and all cognate subjects was rudimentary. No such proposition could then have been enunciated as that every lawful man is bound (exceptions ex pected) to use in all his doings the care and caution, at least, of a man of average pru dence to avoid causing harm to his neigh bors, and is entitled in turn to presume that they will use reasonable care both for him and for themselves. Now it has become a commonplace, and the wayfarer who reads, as he approaches a railroad crossing, the brief words of warning, "Stop, look, listen," little thinks that they sum up a whole his tory of keen discussion. The standard of a reasonable man's conduct has been taken by
