had said that “rules of law (νóμιμα) are made by men; atoms and void (i.e., the unoccupied space in which the atoms exist) exist by nature.”21 What, then, did the Greek philosophers mean by ‘nature’? Certainly it was not what it meant to the biological evolutionary thinking of the nineteenth century. To the latter the ‘natural’ apple would be the wild crab apple, from which the apple of the orchard has been developed by cultivation. To the Greek very likely it would have been the golden apple of the Hesperides. In Latin Φύσις (literally growth) is translated as natura. Lucretius translated the περίΦύεος of Epicurus as de rerum natura. How things grew, or perhaps how they came into existence, could be expressed by how they were born. Applied to things ‘nature’ seems to be the ideal of the thing in its highest perfection. Applied to laws and institutions it appears to have meant the law or institution in its most perfect form.
A distinction which Aristotle drew in the passage quoted from the Nicomachean Ethics came down into modern law as a distinction between mala in se and mala prohibita. As Blackstone put it, the former are actions which are naturally and intrinsically wrong while the latter are actions which are in themselves indifferent but become wrong “according as the municipal legislator sees proper for promoting the welfare of the society and more effectually carrying on the purposes of civil life.”22 What this came to is that the older infringements of the social interest in the general security were recognized in the formative era of American criminal law as mala in se. But newer methods of infringement, becoming antisocial under the conditions of today, in which all manner of mechanical means of endangering life and limb are invented and in operation, have to be the subject of legislation and are said to be mala prohibita.23 The distinction in this form has not been satisfactory in its results.
“Law must be stable and yet it cannot stand still. Hence all thinking about law has struggled to reconcile the conflicting demands of the need of stability and of the need of change.” Thus I began my lectures on interpretations of legal history a generation ago.24 Aristotle might have said that the universal precepts of the natural or general (κοινóς) part of law, being immutable, maintained stability, while the part which rested on opinion for the time being and took form in legislation responded to the need of change. Here an analogy was made use of which has played a great part in juristic thought—the analogy of three regular and predictable phenomena of physical nature: the return of the seasons, the succession of the phases of the moon, day and night. As Socrates is reported in Plato’s Minos to have put it, fire burns and water flows in Greece, in Persia, and at Carthage. The analogy of the physical order of the universe to the moral order and to the legal order has always appealed strongly. Indeed as the psalmist reflected on it and thought of the order of the universe as reflected in the moral law, as it stands in the Psalm de profundis in the Vulgate, he exclaimed, “Because of Thy law have I abided Thee, O Lord.” Because of the stable character of the phenomena of external nature and of the moral order he had faith in the Eternal that makes for righteousness.
Differentiated social control in the stage of the strict law led to distinction of the enacted or imperative from the traditional element in the positive law. A resulting exclusive preoccupation of jurists with positive law led analytical jurists to develop a distinction suggested by Aristotle. Austin distinguished what he called ‘necessary’ principles, notions, or distinctions, which were inevitable constituents of any system of law, since no “system of law as evolved in a refined community” could be imagined coherently “without conceiving them as constituent parts of it.” On the other hand, he saw other principles, notions, and distinctions which were not necessary in that “an expanded system of law could be imagined without conceiving them as constituent parts of it.” He considered that these “rest upon grounds of utility which extend through all communities” and, “as they are obvious in all refined communities. . . occur very generally in matured systems of law.”25 Austin’s necessary constituents of a matured legal system are deduced from his definition of law as the aggregate of rules established by political superiors, that is, “by persons exercising superior and subordinate government in independent nations or independent political societies.”26 Both the necessary and the general principles, notions, and distinctions may in form be either traditional or legislative. But the distinction is made as to positive law. The necessary principles are logically necessary as involved in the very idea of a system of positive law. The general but not necessary principles, as Austin saw them, were established on general grounds of utility as it made itself felt among different peoples. Both would be included in Aristotle’s κοινòν δìκαιον.
It may be that an idea that the method of dichotomy is the exclusive method of classification, an idea no longer held,27 is the explanation. At any rate, except as Aristotle suggests, without expressly setting them forth separately, three categories, namely, natural, general, and local, more or less, however, identifying the general type with the universal, but setting it between the natural as resting on customs of all civilized peoples, and the local resting on local usage and local legislation, philosophical jurists from the Greeks to the present have generally distinguished two types, natural and positive. In the last century Austin distinguished necessary from general precepts and institutions. Historical jurists distinguished traditional from imperative precepts and institutions.
These distinctions, philosophical, analytical, or historical, belong to later modes of juristic thinking. But the distinction made by Aristotle in the Nicomachean Ethics has had a long and fruitful as well as eventful history in the science of law and is the subject of lively debate today. Aristotle’s idea of a law common to the Greek city-states appears in the Roman law books as an idea of a ius gentium. We first find this term in Cicero. But he implies clearly that it was older than his time, telling that it was distinguished from ius ciuile, the strict law of the Roman city-state, by the maiores, the lawyers of the past.28 In another place he speaks of it as a body of legal precepts assumed to exist everywhere.29 It is true in a number of places he assumes that the ius gentium is universal because it is natural; because it has its basis in natural reason.30 In one place he speaks of it as a matter of natural law.31 Thus like Aristotle he was not assured as between a threefold strict law, law of peoples, and natural law, or a twofold positive law and natural law in which the positive law had a universal element and natural law that element as something dictated by nature. Pomponius, in the second half of the second century, uses the term to mean legal institutions known among all peoples.32 In the Veronese codex of the Institute of Gaius, the Roman Blackstone,33 there is a chapter heading (in a later hand) de iure ciuili et naturali, but the first section of Book I speaks only of the ius gentium. The first and part of the second sentence of the section have disappeared in the only manuscript. But they are quoted by Justinian and the section no doubt read thus: “Every people that is governed by statutes and customs observes partly its own peculiar law and partly the common law of all men; but what natural reason establishes among all men is equally followed by all peoples and is called ius gentium, as the law which all peoples make use of.”34 He often seems to identify ius gentium with naturalis ratio. But it is not so clear that he identifies ius gentium with ius naturale. Naturalis ratio is put as what establishes ius gentium among all men.35 But the later jurists of the classical period often speak of the ius gentium as a branch of the positive Roman law to which they refer different doctrines and institutions.36
Although the extent to which a general body of precepts derived from contact with Greek traders, merchants, and bankers, and affected by reading Greek philosophers, existed as a recognized part of the Roman law of the end of the republic, may have been exaggerated in the last century, the extreme skepticism which would label Gaius’s statement contrasting the ius ciuile with the ius gentium and his promise to tell us to which of the two the several legal institutions he will expound belong, ‘pure fantasy,’37 seems equally exaggerated. Such a combination of comparative jurisprudence and rational speculation is not an isolated phenomenon in legal history. An example may be seen in the development of
