I

Grotius wrote DJBP against the backdrop of the successive wars between Protestant and Catholic princes on the Continent, now known as the Thirty Years’ War. Deeply concerned by the continuing atrocity of war across Europe, Grotius hoped to show that most of the violence undertaken there should not have happened in the first place. In his view, the majority of the common causes of war at the time, including those based on religion, could not be justified, for they went against certain ‘right [jus]’. To make this point, however, he first needed to consider what ‘right’ might mean, which was precisely the topic of Book 1, Chapter 1 of DJBP. There, Grotius discussed that jus had three senses, one that meant what was just, another that signified the moral faculty of a person, and lastly law.Footnote ¹² These discussions of jus are important because the subsequent part of DJBP was in essence a comprehensive examination of various causes of war and conduct in warfare in light of these three senses of jus. What violated any of these three ‘rights’ was deemed inappropriate.

In the explication of the third sense of jus as law appears the systematic outline of Grotius’ divisions of law, of which divine positive law was part. Versions of his legal system are found in his earlier works, but the one in DJBP is the most detailed and complete. By positing clearly the categories and divisions of law at the beginning of DJBP, Grotius was able to discuss by which law certain actions or motivations may or may not be regarded as unlawful in the rest of the treatise. This legal treatment of warfare was largely intended to expose the appalling irreverence of the European countries to all kinds of law, but it was also a response to the stringent Christian pacifism that insisted on forbidding all Christians from taking up arms. In the ‘Prolegomena’, Grotius remarked that his legal expertise would contribute to avoiding both extremes and to seeking the lawful extent of war for Christians as well as non-Christians, and to this end he would be the first one who successfully and systematically distinguished different laws.Footnote ¹³

Grotius divided all laws first into natural law and positive (voluntary/volitional) law. Natural law was the dictate of right reason, and was valid regardless of any external authorization including that of God, while positive law had its legal force from the will of the lawgiver. Natural law and positive law made two completely separate categories, but no positive law could violate natural law. Positive law was further divided into divine positive law and human positive law, depending on who the lawgiver was. Divine positive law was either universal or particular, the former intended for all human beings while the latter binding only one nation or people. Human positive law was either civil law that was legislated by the civil power of one state, or the law of nations that was derived from the will of many states.Footnote ¹⁴

As will be demonstrated in the course of this article, the most innovative part of these divisions of law was the idea of divine positive law. The novelty was particularly salient in the Protestant legal discourse, because there had been no clearly established concept of divine positive law before Grotius; the common divisions of law among Protestants used to be divine law, natural law, and human law. The term positive law was also used, but it was mostly coterminous with human law or the command of the magistrate.Footnote ¹⁵ Divine law was rarely identified as positive law, as it was tied far closer to natural law in Protestant reformers’ efforts to fend off Catholic soteriology and to justify resistance against Catholic rulers. As Sarah Mortimer has shown, Protestant reformers from Martin Luther onwards vigorously denounced the Catholic idea that there were certain praiseworthy but not absolutely obliging actions for spiritual perfection. For the likes of Luther and his collaborator Philip Melanchthon, the idea that some decrees of God were only optional was at the root of the erroneous conception of merit in salvation. These reformers instead regarded all laws of God as an absolutely binding precept, so that there would be no human action that was superfluous and therefore meritorious.Footnote ¹⁶ The close equation of divine law and natural law also had political implications. It meant that the realm of human politics was governed by divine law as well as natural law, since all human actions now had religious implications. In this scheme, the rule of false religion generated a ‘duty’ to resist in accordance with divine law, rather than the ‘right’ to resist in the light of an original human compact or the common good in the realm of pure human politics.Footnote ¹⁷

These were certainly some key ‘Protestant’ developments in thinking about law and obligation, and Melanchthon’s contribution was potentially no less significant than Grotius’.Footnote ¹⁸ Nevertheless, neither his Loci communes (1635) nor Philosophiae moralis epitome (1538) gave rise to a new and intense study of natural law among Protestant scholars as DJBP did. Although he set out a new relationship between natural law and divine law through his anti-Catholic campaign, Melanchthon upheld the conventional view that the epitome of natural law was expressed in the Decalogue, the view that most of his opponents shared. If anything, by tying natural law and divine law more closely than ever, the link between natural law and the Decalogue became tighter at the hands of Melanchthon and in the ensuing Protestant legal discourse. This framework is far from conducive to a clear distinction between the ‘natural and supernatural light’, and indeed those who paid high regard to Grotius criticized Melanchthon for owing too much to earlier traditions.Footnote ¹⁹ Grotius’ separation of natural law and divine positive law, therefore, was what made him stand out in the Protestant legal tradition, and the idea of divine positive law deserves much more attention than it has received.

Nevertheless, the term divine positive law, along with the divisions of law that it espoused, was not Grotius’ invention. Influential Catholic theologians such as Francisco Suárez and Leonardus Lessius had been thinking in these terms prior to Grotius. Although what they meant and intended by the term divine positive law was not quite the same as Grotius, they did divide all temporal laws into natural law and positive law, and then positive law into divine positive law and human positive law. Moreover, it can be reasonably assumed that Grotius took these divisions of law in the 1610s reading Catholic treatises, the time when the emerging religious ideas in Grotius and his friends turned out to be less compatible with the conventional Protestant idea of divine natural law. To understand the Catholic legacy of the term divine positive law, the next section explores how it gained currency among Catholic theologians from the early sixteenth century and became a powerful weapon of the Roman Church by the beginning of the next century.

II

In Catholic scholastic tradition, the standard categories of law were eternal law, natural law, human law, and divine law. The influential account of these laws is found in Thomas Aquinas’ Summa theologiae, Ia IIae, questions 90 to 108. According to him, eternal law was the order of the universe as governed by divine reason, and natural law the participation of rational creatures in eternal law. While natural law would broadly direct rational creatures to the right end, further specifics were necessary in individual circumstances. To supplement the generality of natural law, human law was devised by human reason, and divine law, consisting of the Old Law and the New Law, had been given by God. In the context of this article, what should be noted here is that these Thomistic categories of law were established primarily based on their relationship with eternal law, rather than on their legal nature. Thus, while the positive nature of human law and divine law was recognized, the contrast between, or the division of, natural law and positive law was not brought to the fore. For this reason, the exact distinction between natural law and divine law remained unclear, and later readers of Summa would deal with this ambiguity. Meanwhile, Aquinas did make a distinction between natural and positive in his discussion of rights in IIa IIae, question 57, but the positive rights only meant those established by human authority.

Despite the ambiguity it carried, Aquinas’ discussion of law in Summa became the common reference point of numerous legal treatises and commentaries in the sixteenth-century Catholic world. Although Aquinas was not necessarily regarded as a mainstream orthodox thinker during his lifetime, his posthumous reputation continued to rise until Pope Pius V proclaimed him a Doctor of the Church in 1567. The study of Summa particularly flourished at the University of Salamanca from the early sixteenth century, led by the Dominican Francisco Vitoria and his students. Taking the discussion of law in Summa as a starting point, they delved into the nature of obligation and the problem of justice regarding various contemporary issues.Footnote ²⁰

Over two centuries after Aquinas’ time, however, these Thomists felt the greater need to clearly distinguish natural law from divine law. As Catholic Spain and Portugal expanded their territories across the Atlantic from the late fifteenth century, they encountered people of a completely different culture and religion. Concerning the treatment of these strangers, theologians disputed over what kind of justice and law might be applicable to them, and in this debate arose the idea of natural law as a universally binding law which the native people in the New World should also observe.Footnote ²¹ As it became quite obvious that these Amerindians, who had no knowledge of Scripture, were not supposed to be bound by either the Old or New Law, the difference between natural law and divine law needed to be pronounced more explicitly.

Facing these new circumstances, which had not existed in Aquinas’ time, leading Catholic theologians started to employ the term divine positive law. In his commentary on Summa, Francisco Vitoria, the founder of the School of Salamanca and one of the major participants in the disputes concerning Amerindians, divided temporal law into divine law and human law and then the former into divine natural law and divine positive law.Footnote ²² In his view, natural law and divine law in Aquinas’ account made more sense when they were termed divine natural law and divine positive law. By using the term divine positive law in particular, Vitoria wanted to emphasize the necessity of promulgation for its validity, unlike divine natural law, which did not require promulgation to be binding. Luis de Molina, an influential Jesuit theologian in the second half of the sixteenth century, also divided divine law in the exact same way, positing that divine positive law was a set of commands laid down by God or Christ concerning matters that did not pertain to natural law.Footnote ²³

Despite their use of the term divine positive law, however, neither Vitoria nor Molina went so far as to renew Aquinas’ original legal categories. They instead presented themselves as working within Aquinas’ idea of divine law, suggesting that divine law in fact had traits of positive law and could be distinguished from natural law. In this effort to maintain the Thomistic categories, they first divided temporal law into divine law and human law, and then divine law into divine positive law and (divine) natural law, instead of creating the independent category of positive law. The danger of dividing temporal law first into natural law and positive law was clear, as the category of divine law would turn out to be unnecessary.

There was, however, one who took this risk and introduced new divisions of law, openly abandoning the category of divine law. In his seminal treatise De legibus ac Deo legislatore (1612), the prominent Jesuit Francisco Suárez explicitly rejected the necessity of divine law as presented by the Angelic Doctor and argued for the necessity of the category of divine positive law, along with a new legal system in which temporal law was first divided into natural law and positive law. To him, it appeared that the idea of divine law in Summa was ill-defined and its function overlapped too much with that of natural law. In Suárez’s summary, Aquinas offered four reasons for the necessity of divine law, namely to direct human beings to a supernatural end, to assist natural human judgement, to supervise interior human acts, and to restrain human beings from all evil. Of those, Suárez claimed, the latter two were already served by natural law, and the former two would be fulfilled by the better-defined concept of divine positive law.Footnote ²⁴ Suárez thus defined divine positive law more clearly and narrowly than his predecessors did, taking distance from the old idea of divine law. In his definition, divine positive law was the divine will expressed in Scripture, specifically concerning external human acts and the order in the Church, that is, the sacraments and clerical hierarchy. For him, it was important that divine positive law concerned external conduct alone, so that its domain did not overlap with natural law, which governed internal actions.Footnote ²⁵ In addition, divine positive law was now exclusively associated with the Church, reflecting the post-Tridentine campaign of the Roman Church against secular monarchs.

At the turn of the seventeenth century, when Suárez was writing De legibus, the authority of the Roman Church was fiercely challenged not just by Protestants but also by those who more generally wanted to empower secular rulers over the Pope. One of the best known struggles with Protestants was the controversy over the Oath of Allegiance, imposed by the Protestant monarch James VI and I upon English Catholics in 1606. The oath required Catholics in England to swear the supremacy of the English king over the pope so that they would not pose a threat to the civil order of England. Around the same time, some high-profile Catholic authors such as the Scottish jurist William Barclay and the Venetian friar Paolo Sarpi went on to undermine the temporal authority of the pope, trying to protect the civil magistrate from papal intervention. Suárez would publish a hefty tome, Defensio fidei, specifically attacking James’ Oath of Allegiance in 1613, but a more academic De legibus was in part also a response to these challenges to the authority of the Roman Church over the Catholics in all realms.Footnote ²⁶

In particular, the idea of divine positive law as proposed in De legibus was a powerful weapon against the theory of royal authority upheld by James VI and I and William Barclay. These anti-papalists argued that there was no earthly agency that could lawfully challenge monarchs, because monarchs received a special mandate to govern directly from God. This idea, known as the Divine Right of Kings, was often underpinned by verses and episodes in Scripture where the obedience to the secular authority, even to tyrants, was commanded by God.Footnote ²⁷ In stark contrast, Suárez’s idea of divine positive law rested upon the thought that the word of God first and foremost empowered the Church and its clergy. In his legal system, the civil law of secular rulers was categorized into mere human positive law that only concerned temporal goods and was thus far less important than other laws pertaining to the supernatural end.Footnote ²⁸ Suárez did recognize the legitimacy of the civil communities and their authority, but for him the ultimate end of all human communities was undoubtedly spiritual. In the sense that the Church had the special divine mandate to direct human beings to this ultimate spiritual end, its authority always exceeded that of the secular state. In De legibus, these political implications of divine positive law remained largely implicit, but in Defensio fidei its full polemical force in defence of the Roman Church was unleashed.

While Suárez was the one who most explicitly laid down the distinctly Catholic concept of divine positive law along with the new divisions of law, his influential colleagues were thinking in similar terms, fighting the same battle. In his widely read commentary on Summa, Leonardus Lessius, a Jesuit who received Suárez’s teaching in Rome, presented the same divisions of law as his teacher’s and explained that the subject matter of divine positive law was the ceremonies and government in the Old Testament and the sacraments in the New Testament.Footnote ²⁹ Against Barclay’s anti-papal argument that clerical hierarchy was merely of human positive law, Cardinal Robert Bellarmine insisted that the ground of ecclesiastical order and authority was, in contrast, directly from the divine commands in Scripture.Footnote ³⁰ Although Bellarmine did not use the term divine positive law as often as Suárez, the exclusive association between biblical precepts and the Church was evident.

In short, by the beginning of the seventeenth century, the Thomistic idea of divine law had been reconfigured as the positive law of God specifically concerning the government and sacraments of the Church. This shift entailed a new emphasis upon the division between natural law and positive law, with divine positive law being seen as a branch of positive law rather than divine law. In the context of the fierce politico-religious controversies between the Roman Church and secular sovereigns, the idea of divine positive law was closely bound up with the papalist position and was employed to underline the divine authority of the Church.

As a reader of these Catholic treatises, especially Suárez’s De legibus and Lessius’ commentary on Summa, Grotius could not have missed the sacerdotal implications of the idea of divine positive law.Footnote ³¹ Simultaneously, however, the Catholic effort to distinguish clearly divine law from natural law by introducing the idea of divine positive law would have appealed to Grotius and some of his Dutch Protestant friends in the 1610s, for the new idea resonated with their growing conception of the Christian religion. In transforming the Catholic concept into a Protestant one, the flourishing historical scholarship of the Old Testament in his scholarly circle also helped. To this Protestant appropriation of divine positive law, we turn next.

III

Less than two decades after the publication of those first-rate papalist tracts, the author of DJBP managed to devise an entirely different conception of divine positive law. For Grotius, it meant all the commands of God given to human beings as written in Scripture, regardless of their relation to the Church. Within divine positive law, there were universal ones given to all mankind and particular ones given to one nation, and the scope of this law could be discerned by the moment of its legislation. In Grotius’ account, there were three moments that indicated the universal scope of a divine command: first, immediately after the Creation; second, after the Flood; and finally, under the Gospel of Jesus Christ. While the universality of these divine precepts given in the former two moments rested on a different premise than the universality of the Gospel, Grotius did not make a clear distinction here. Divine precepts given in the former two moments were considered universally intended because Adam and Noah were the progenitors of all mankind, whereas the universality of the Gospel was expressed in the word of Christ. Indeed, Grotius was of the view that, in reality, the Gospel only bound Christians, whereas those laws given to Adam and Noah could bind a wider range of people. Nevertheless, his main point here was that all these commands were divine positive law rather than natural law, even though they were intended for all human beings. And because they were positive law, their obligation did not arise until human beings had explicit knowledge of those commands by sufficient promulgation.Footnote ³²

This new definition of divine positive law, along with its new subdivisions, would have a tremendous impact upon the European intellectual landscape in numerous ways, but in relation to natural law, it marked two major departures from orthodox Christian discussion. First, the Ten Commandments in Exodus and Deuteronomy were neither natural law nor universally binding positive law of God. Rather, they were a mere particular divine positive law given to the Jews alone, from which a universal obligation could not be drawn straightly; all the positive precepts in the Decalogue conformed to natural law, for no positive law could violate natural law, but they were not in themselves universally applicable. Second, the law of Christ was not the perfection or extension of moral law; they belonged to two different categories of law, the former positive law and the latter natural law. Like the positive precepts of the Decalogue, the law of Christ conformed to natural law, but it was now implausible to understand the obligation of natural law through Christ’s law, for the two laws had completely different origins and grounds of obligation.

Grotius’ own example of this distinction between the Gospel and the law of nature touched on marital ethics. Conventionally, Catholic scholastics and Protestant reformers alike upheld that polygamy, divorce, and concubinage were more or less against natural law, on the basis that Christ had obliged strict monogamy. Although few exactly equated natural law with Christ’s law, they were at pains to show how monogamy was the universal and natural norm and how those polygamous practices of the Old Testament patriarchs had been an exception by special divine mandates.Footnote ³³ Under Grotius’ new division of law, on the other hand, there was no longer the need to ‘sweat to prove what the Gospel forbids is also illicit by natural law’.Footnote ³⁴ For Grotius, the fact that God had ever permitted polygamy, divorce, and concubinage meant that they did not violate natural law, while there were more stringent marital ethics for those who pledged to observe the positive law of Christ.

When, and how, did he come to devise this new conception of divine positive law? Prior to the 1610s, Grotius did not distinguish divine precepts from natural law clearly. The manuscript text of his De jure praedae, first written in 1604–6 and revised in 1607–8,Footnote ³⁵ suggests that Grotius upheld the orthodox Christian view that the law of Christ was no stricter than the law of nature, for both were instituted by the will of God.Footnote ³⁶ At times, especially when he discussed the natural rights of non-Christians, heavily referring to Catholic theologians, the Dutch lawyer was more inclined to discuss that the divine law of the Christian faith might be something different from universal natural law.Footnote ³⁷ Nevertheless, in all his known writings in the 1600s, Grotius broadly maintained the thought that natural law was a subcategory of divine law, rather than a different kind of law. Moreover, the idea of divine positive law itself seems to have been alien to him then, as positive law only meant human positive law.Footnote ³⁸ Thus, although Grotius did sometimes try to separate divine law from natural law in the 1600s, it is likely that he did not have adequate legal terminology to address the separation, particularly before Suárez’s De legibus came out in 1612.

Grotius’ earliest attempt to separate natural law from divine law clearly by using the term divine positive law was in De imperio, composed around 1614–17, and De satisfactione (1617). Especially from his references in De imperio, we could tell that he was familiar with Suárez’s De legibus as well as the broader Roman Catholic context in which the Jesuit theologian was active. But already at this point, Grotius was using the term divine positive law in his own sense rather than in the Catholic sense, though less elaborately than he would do in DJBP.

In De imperio, the term was employed when he explained those matters that were beyond the civil magistrate’s jurisdiction. The tract emerged in the fierce Dutch controversy over the supreme civil magistrate’s jurisdiction in religious matters, in which controversy Grotius sought to defend the civil magistrate’s power. To this end, he first clarified what did not fall under that jurisdiction, and then argued that none of the contested religious matters, including holding synods, appointing pastors, and adjudicating excommunication, belonged to that category. According to Grotius, those matters prescribed or forbidden either ‘by their very nature’ or ‘by divine authority’ were beyond the civil magistrate’s control, each pertaining to the realms of natural law and divine positive law. With regard to divine positive law, Grotius detailed that it was given to an individual, to a people (like the Israelites) or to all human beings. Unlike its Catholic version, the subject matter of divine positive law was not confined to the external rites and order of the Church, nor was the law exclusively given to the clergy. The entire Gospel was categorized into universal divine positive law, and in the same category were the divine precepts given at the Creation and right after the Flood. Those precepts, Grotius explained, set a limit to the civil power, but what lay beyond them was fully under the supreme magistrate’s jurisdiction.Footnote ³⁹ For all this initial theoretical setup, however, in De imperio the distinction between natural law and divine positive law did not stand out as both laws indicated the higher laws from God which human authority could not violate. Indeed, for this reason, Grotius sometimes referred to both laws as ‘divine law’.Footnote ⁴⁰

In De satisfactione, on the other hand, the distinction between natural law and divine positive law played a more important role. The treatise was a refutation of the Socinian thought that the death of Christ on the cross did not affect the terms of salvation at all, because God could always freely choose to forgive sins like a private creditor and to save those who earnestly followed His commands. Grotius’ main point, which is often called the governmental theory of atonement, was that God should be seen as a just ruler who did require satisfaction for human trespasses against His law, rather than as a private creditor. Based on this idea, Grotius went on to argue that God could sometimes relax or dispense with the punishment of breaking His law, because that law was positive law, which could be altered by the lawgiver’s will, rather than natural law, which could never be relaxed or suspended.Footnote ⁴¹ This account contains a sharper contrast between natural law and divine positive law, as well as the notion that the law of salvation directed to all mankind was part of the latter.

It may be then suggested that the key elements of his new idea of divine positive law were already in place in the 1610s. Not only was he using the new term but he also came up with the novel classification of divine positive law comprising the universal and particular, parting from the classic division of scriptural precepts into the Old and New Law. The turning point in the 1610s was no coincidence, because at that time he was at the forefront of dynamic theological and intellectual developments in his native land, developments that shaped his idea of divine positive law. In particular, the two columns of universal divine positive law, one the Gospel and the other the divine precepts given to Adam and Noah, could be attributed respectively to the development of Remonstrant thinking following the Five articles of Remonstrance (1610), and to the reception of Jewish legal scholarship among Protestant Hebraists in the Dutch Republic.

The Five articles were drawn up by Johannes Wtenbogaert after the death of Jacobus Arminius in 1609. Arminius and his followers upheld that election was conditional and grace resistible, rejecting the Calvinist doctrines of unconditional election and irresistible grace. Those who subscribed to the articles were referred to as Remonstrants, and their opponents Contra-Remonstrants. Involving leading ministers as well as high-ranking statesmen of the Dutch Republic, the controversy between the two intensified until the Remonstrants were officially condemned at the Synod of Dort in 1619. As a close associate of Wtenbogaert, Grotius was drawn into these struggles and was eventually imprisoned as the Remonstrant side lost the politico-religious battle.Footnote ⁴²

Although the Remonstrants initially started off as Arminius’ followers, in the course of the intense battle against Contra-Remonstrants, they developed their own understanding of the Christian religion distinct from Arminius’. The Remonstrants took the idea of human responsibility much more seriously than their teacher, insisting that God would never punish human beings for things over which they lacked responsibility. This attention to human responsibility was the ground of the Remonstrant rejection of the Contra-Remonstrant doctrine of Original Sin that human beings had come to have irrevocably impaired reason because of it and could never contribute to the process of salvation. For Remonstrants, the impairment of reason could not have been the consequence of Original Sin, because such punishment had never been made explicit by God in the Garden of Eden. The same logic applied to their rejection of the doctrine of absolute predestination; eternal damnation would take place only when an individual human being was sufficiently informed of the terms of salvation in Christ and then made a wilful and free choice not to abide by them.Footnote ⁴³

Through these refutations of the Contra-Remonstrant doctrines, the Remonstrants developed not only a more positive view of human reason unimpaired by Original Sin, but also the idea that Christian teaching was not part of natural human obligation. For otherwise, those who had no knowledge of Scripture were to be damned helplessly, which seemed utterly unreasonable to Remonstrants. This was the kind of problem that the Catholics in the Iberian Peninsula had encountered about a century earlier, one that gave rise to the necessity of separating natural law from divine law.

In their own early seventeenth-century Dutch contexts, then, the Remonstrants faced the need to distinguish clearly the law of Christ revealed in Scripture from the law of nature. A fitting example of this line of thinking can in fact be found in Meletius, Grotius’ short piece composed around 1611. While it emerged from his deep desire to end religious strife through a consideration of minimal common ground among Christians, part of it also put forward the idea that Christian obligation was distinct from natural obligation. In his view, Christ’s law was more demanding than natural law, and its knowledge could only be attained by reading Scripture, not by exercising natural reason.Footnote ⁴⁴ This understanding of Christ’s law was not quite compatible with the orthodox Protestant idea of divine natural law, precisely as the Contra-Remonstrant Antonius Walaeus pointed out in his letter to Grotius in 1612.Footnote ⁴⁵ Nevertheless, Grotius continued to develop the Remonstrant vision of Christianity throughout the 1610s, conversing with the likes of Gerardus Vossius and Simon Episcopius.Footnote ⁴⁶ The idea of divine positive law in the works of Lessius and Suárez, then, would have appealed to him as a useful concept to express the extra-natural characteristics of Christ’s teaching, insofar as it indicated the entirety of His commands rather than certain clerical precepts. The Gospel of Jesus Christ was thus classified as universal divine positive law.

Let us now turn to the other component of Grotius’ universal divine positive law, namely the divine precepts given to Adam and Noah. The thought that the Adamite and Noahide precepts bound all their posterity had its roots in the Jewish tradition, in which those precepts informed the obligation of Gentiles.Footnote ⁴⁷ In that tradition, universally binding were these precepts, rather than the Ten Commandments, which were rendered specific to the Jews as part of the Mosaic covenant. The Adamite and Noahide precepts were more commonly referred to as the seven laws of Noah among the Jews, consisting of six prohibitions against idolatry, blasphemy, murder, sexual immorality, theft, and eating blood (or limbs of living animals), and one positive command to establish courts of justice. The Talmudic idea of Noahide law was most influentially discussed in the medieval rabbi Moses Maimonides’ Mishneh Torah, a comprehensive guide to Jewish law. It was no coincidence that Grotius took notice of this idea in the 1610s, because that was precisely the time when the study of the Mishneh Torah took off and his Hebraist friends at Leiden began consulting it.

From the late sixteenth century, the newfound University of Leiden was the most vibrant intellectual centre of Hebraic study in Protestant lands, and was also the alma mater of Grotius. Although it is difficult to uphold a clear-cut confessional division in early modern biblical scholarship, as Timothy Twining has recently shown,Footnote ⁴⁸ the Protestant enterprise of investigating the Old Testament with the intention to utilize the legal, political, and ecclesiastical arrangement of the first people of God was more intense and widespread as a whole.Footnote ⁴⁹

This Protestant interest in the public life of the Old Testament Jews led to the growing reception of the Mishneh Torah from the 1610s. There had been highly qualified readers of Maimonides in the late sixteenth century, but it was not until the early seventeenth century that Protestant Hebraists explicitly referred to Noahide law. One key pioneer in this regard was Petrus Cunaeus, a Leiden scholar and friend of Grotius, whose widely acclaimed De republica Hebraeorum (1617) was arguably the first treatise by a non-Jew that made extensive use of the Mishneh Torah.Footnote ⁵⁰ In the book, the idea of Noahide law mainly appeared in his account of the postbellum settlement of the ancient Israelites, in which they imposed the seven Noahide precepts on the conquered. Cunaeus explained that, while these precepts had been given before Abraham, the founder of the Israelite Commonwealth, the Israelites kept them because they had been given to the first fathers of mankind.Footnote ⁵¹

As a leading scholar who studied at Leiden and maintained a close relationship with the likes of Cunaeus throughout the 1610s, Grotius would have been one of the first to notice the Jewish idea of Noahide law. With other Protestant Hebraists at Leiden, Grotius regarded ancient Israel as a useful constitutional model for the Dutch Republic, taking great interest in the laws kept by ancient Israelites from his late teens.Footnote ⁵² His friendship with Cunaeus did not waver during the post-Remonstrance theological controversy. Theologically, Cunaeus was no confessed Remonstrant, but he was sympathetic to Grotius’ view of church and state in part undergirded by the constitution of ancient Israelites, and was keen to continue their conversation on the Hebrew Republic.Footnote ⁵³ Through his exposure to these new trends in Protestant Hebraic scholarship, Grotius came to classify the Noahide law as universal divine positive law, while relegating the Decalogue to particular divine positive law.

In sum, Grotius’ idea of divine positive law was a product of the marriage between the lively intellectual developments in his Protestant country and the recent systematization of law in the Catholic world. As these contexts suggest, Grotius was by no means a lone innovator; the main building blocks of his legal system can be attributed to earlier traditions and contemporary scholarly achievements. Nevertheless, it was his genius to bring together these wide-ranging and cutting-edge ideas and to draw up a classification of law that was shorn of Catholic sacerdotal implications and was compatible with his defence of the authority of the lay supreme magistrate. It should be underlined that, although he was not the first to separate natural law from the Gospel or to introduce the Jewish idea of Noahide law to Protestants, he was the first to classify the Gospel and Noahide law as universal divine positive law and the rest of the scriptural precepts as particular divine positive law. By so doing, he separated natural law clearly from the Decalogue as well as from the Gospel, transforming not only the study of natural law but also the broader inquiries into the nature of the Christian religion and of human obligation. It is thus no surprise that early reactions to DJBP were more about Christ’s law than about natural law.Footnote ⁵⁴ The full picture of these transformations, however, is beyond the scope of this article. Instead, I would like to bring this article to an end by outlining the centrality of Grotius’ idea of divine positive law in the post-DJBP Protestant natural law scholarship.

IV

Although a large part of Grotius’ idea of divine positive law owed to the specific Dutch contexts in the 1610s, his systematic presentation of it in DJBP appealed to a wide range of Protestant divines and lay scholars. As excellently documented by Richard Tuck and Knud Haakonssen, among others, Grotius’ discussion of law offered an intellectual framework to those Protestants who broadly supported the civil magistrate’s power over religion. But as Sarah Mortimer has shown, it was also taken up by those Protestants who shared the Grotian-Remonstrant idea that Christian ethics was invariably more demanding than natural law ethics.Footnote ⁵⁵ The works of John Selden, Thomas Hobbes, Samuel Pufendorf, Richard Cumberland, John Locke, Jean Barbeyrac, and Christian Thomasius were all built upon these new Protestant approaches to law, civil supremacy, and religion pioneered by Grotius.

The sweeping impact of Grotius’ legal theory among Protestants, however, did not mean that Grotius’ classification of law was received and studied exactly as he presented it. On the contrary, only a few faithfully retained his distinction between natural law and divine positive law, including the part that natural law was obliging by natural human reason. It would have been for those wildly varying responses to Grotius that the novelty and legacy of his idea of natural law have been disputed among modern historians for over a century. In order to understand the seismic impact of his new theory of law as his contemporaries did, we should pay attention to the new questions that it generated, rather than the variegated answers and methods with which his readers and he himself came up.

Once natural law was detached from the Decalogue and the Gospel, the most pressing question became how human beings could understand natural law obligation without the direct aid of those divine precepts written in Scripture. This new problem generated various answers as well as further enquiries: Grotius’ was founded upon the right reason and human sociability, while Cumberland’s centred on scientific observation of nature.Footnote ⁵⁶ Selden chose to identify natural law with the Noahide law, thereby stimulating the discussion surrounding the exact distinction between natural law and the universal divine positive law given to Adam and Noah.Footnote ⁵⁷ Meanwhile, Hobbes derived the content of natural law from the principle of self-preservation, although he did not admit its obliging force until its enactment by the sovereign.Footnote ⁵⁸ Again, we should not be distracted by the question of how novel each of these answers was, especially the one put forward by Grotius himself. As a number of historians have pointed out, a close study of human nature and human society had taken place, potentially far more systematically and elaborately, among earlier scholastics, humanists, and civil lawyers, and several important roots of Grotius’ discussion of natural law can be found in them.Footnote ⁵⁹ In this sense, it is entirely plausible that what Grotius proposed as natural law obligation had little novelty. Nevertheless, the question he opened up by the separation of natural law from divine positive law was unequivocally novel in early modern Latin Christendom.

It is worth highlighting that Samuel Pufendorf, who was appointed to the very first chair in natural law at Heidelberg and pioneered the post-Grotian Protestant legal scholarship, broadly maintained the Grotian distinction between natural law and divine positive law. Although he upheld the ‘voluntarist’ position that natural law was obliging because it ultimately corresponded to what God willed for humanity, this divine will should not be located in the Decalogue, the Gospel, or even in the Noahide law. In the opening part of his Specimen controversiarum circa jus naturale (1678), a defence of his earlier treatise De jure naturali et gentium (1672), Pufendorf most explicitly criticized the attempt to investigate natural law obligation either in terms of the divine precepts in the Jewish tradition or Christ’s law, for both belonged to the separate category of positive law.Footnote ⁶⁰ It was upon this Grotian separation of natural law from divine positive law that Pufendorf built his own ‘science’ of natural law, disagreeing with the Dutch lawyer on some key points but holding the same question.

The Grotian idea of divine positive law was thus central to his followers’ new enquiry into natural law, but it was also what Grotius’ critics took issue with. As Hans-Peter Schneider, Martin Mulsow, and Frank Grunert have shown, several German readers of DJBP campaigned for the Lutheran-Melanchthonian ‘Christian natural law’ against the ‘secularizing’ Grotian natural law.Footnote ⁶¹ Criticizing none other than Grotius’ separation between natural law and divine positive law, Johann Heinrich Boecler and his associates tried to tie the two laws closely together in the manner of earlier Protestant reformers. For Boecler, the separation was not only difficult but absurd, because the fallen human beings could only understand natural law through the divine positive law expressed in the Decalogue.Footnote ⁶² Soon after, Boecler’s friend Caspar Ziegler mounted a longer and sharper attack on Grotius’ thought that Christ had established a superior positive law distinct from natural law. Underscoring the convergence of the positive law of God with the law of nature, Ziegler tried to defend the orthodox teaching that Christ merely perfected the natural law given to Moses in the form of the Decalogue.Footnote ⁶³ Once again, what alarmed these critics was Grotius’ separation of natural law from divine positive law, rather than his idea of natural law per se.

Besides these examples, the receptions of and responses to DJBP were utterly diverse and multifaceted as the ever-growing body of recent studies shows.Footnote ⁶⁴ But those studies have hardly silenced those who are sceptical about the novelty of Grotius for his arguably conventional idea of natural law. In order to cope with the persisting scepticism and to appreciate his impact properly, it should be remembered that it was his division of law involving a new idea of divine positive law, not the idea of natural law in itself, that made his name in the history of natural law. His idea of divine positive law was what enabled the clear distinction between the ‘natural light’ and the ‘supernatural light’, generating an entirely new set of enquiries which simultaneously led to the ‘science’ of human morality apart from Scripture, accelerated the Protestant investigation of Hebraic sources, and gave theoretical underpinnings for the new perception of Christianity as a religion of higher ethics. Grotius was indeed ‘incomparable’ in shifting the very questions that Protestant divines and laypeople had been asking, even if his own answers were not equally groundbreaking.