Given the number of fields in which he made pioneering contributions – international law, natural jurisprudence, secular ancient and modern history, ecclesiology, theology, biblical exegesis, neo-Latin poetry, dramaturgy etc. – Hugo Grotius probably has as good a claim as anyone to the status of the seventeenth century's most prominent man of letters. I deliberately use ‘man of letters’ in favour of the anachronistic ‘intellectual’, and here the tag is doubly appropriate, for we have more surviving letters to and from Grotius than for almost any other seventeenth-century figure: the total in the Briefwisseling van Hugo Grotius (17 vols, 1928–2001) numbers 7,725. It is largely on the basis of these letters that Henk Nellen – who has co-edited five volumes of the correspondence – has produced his excellent biography, which will undoubtedly become, and long remain, the standard biographical reference-point for all subsequent Grotius scholarship. First published in Dutch in 2007, it now appears in a very readable translation by Chris Grayson for Brill, both of whom must be commended for taking on this very important project, and for producing a well-presented book in which I have been able to find very few typographical or stylistic errors.

Henk Nellen's decision to construct the biography around the correspondence is an interesting one, which is justified by the end result. Whereas Grotius' works have been republished in many modern editions, and have been the subject of many interpretative studies of varying quality, the correspondence remains largely in Latin, and its contents – essential to understanding Grotius' political and intellectual lives – could only be synthesised by someone with an intimate editorial knowledge of the letters. Of course, one consequence is that Grotius' books receive only summary treatments, but in many ways this is welcome, for far too many studies have vainly attempted to use the books (especially De jure belli ac pacis) as a kind of ‘key’ to Grotius' intellectual biography. Contrary to such a totalising approach, Nellen is resolutely cautious, preferring, when faced with a problem, to describe all the possible answers that the evidence might support, and then tentatively to rank them by probability (of many examples, one might instance his discussion of the possible reasons for Grotius' last, fateful journey from Sweden at pp. 728–30).

To point out this caution, however, is not to take away from the masses of important new details that are added to our knowledge of Grotius' life and of the world around him. To give only a few examples, we might mention the findings on Grotius' precise role in the Arminian disputes of 1611–18 and his relationship with Oldenbarnevelt; or on the immense societal impact of theological publications, and how that impact was conveyed through, and shaped by, learned correspondence; or on the composition of Grotius' works, their journeys through the publication process (especially through the presses of Johan Blaeu) and their subsequent revision (it is shown conclusively just how much Grotius considered his books as works in progress even after they had been published); or on the importance of neo-Latin poetry for the development of a young scholar's reputation; or on Grotius' character, which can only be described as abysmal, despite the many mitigating circumstances that Nellen loyally brings forward to explain it. Grotius treated not only his enemies but often even his friends – not least G. J. Vossius and (the very understudied) Étienne de Courcelles, who were expending huge energies on publishing his works in the Dutch Republic while he was in exile in Paris – with the utmost haughtiness, ingratitude, and, in the last decade of his life, with what can only be described as an almost manic paranoia.

This mass of information will be of immense use to all scholars of the seventeenth-century, well beyond Grotius specialists. Is it combined with an overarching argument about the nature of Grotius' intellectual career? One key theme identified by Nellen, with which it is difficult to argue, is how much the effects of 1618 marked Grotius: this is unmistakeably a book by a Dutchman writing about a Dutchman, the second of whom spent much of his adult life pining to go home, while simultaneously despising his countrymen for rejecting him. The second, made clear in the subtitle of the book, is Grotius' search for ‘peace in Church and State’. Here Nellen produces much important evidence from the correspondence, and from the correspondence of others who knew Grotius, showing that his irenicism (understood broadly) was a constant feature of his thought.

But some readers might not accept entirely the ‘modernising’ reading of Grotius that is sometimes offered. For the first half of Grotius's career (up to 1618), Nellen himself demonstrates convincingly the extent to which Grotius was an Arminian ‘partisan … no longer open to arguments of the other party’ (p. 207). The ‘toleration’ that he was arguing for was to be imposed from above, by an erastian monarch. If we indulge in a counterfactual, it seems very probable that had Oldenbarnevelt and the Remonstrants triumphed politically, they would have engaged in a steady campaign against the Calvinists, whom they would have condemned as schismatics – Grotius ‘was firmly convinced that tolerance could not extend as far as any accommodation with recalcitrant preachers’ (pp. 212–13) – and if one puts theologians on a scale from radical Calvinist to radical Arminian, Grotius was only prepared, for all his self-proclaimed ‘moderation’, to tolerate the latter (men like Nicolaes van Grevinchoven, Petrus Bertius and Caspar Barlaeus). As for his later, utterly implausible belief in a reconciliation between ‘moderate’ Catholics and Protestants, this seems to have been driven even more by a vitriolic hatred of Calvinists, whom he now thought of as ‘a new religion, self-created … marked by the schismatic tendency that typified all secessions from the mother Church’ (p. 707). It is difficult to disagree with the judgement of his Parisian acquaintance Guy Patin that his later political opinions were those of a ‘harmless madman’ (p. 745), although of course many Remonstrants back in Holland were now seeing Grotius' flirtations with Catholicism as anything but harmless to their cause.

Similar qualifications might be made about some of Grotius' books. De veritate religionis Christianae (1627), Grotius's most popular book until the twentieth century, did indeed offer some developments in Christian apologetics, especially in its resolutely historical justification for the authority of the Bible, but it seems too much to attribute this to irenicism (which involves rejecting Grotius' own account of its genesis: p. 425): apologetics was by its very nature pan-confessional, since it defended Christianity tout court – plenty of clerics eagerly recommended De veritate to their students despite their obvious bigotry on other, inter-confessional issues. Similarly, Nellen's rather secularising reading of Grotius' biblical commentaries (for example, p. 633: ‘Grotius's method was detached from clear theological concepts’) is mitigated both by his own comments and by recent work by others on the centrality of concepts like typology within these books. Partly as a result of the focus on Grotius' correspondence, his enemies can sometimes appear slightly voiceless – the section on the biblical commentaries contains repeated references to unnamed ‘traditional exegetes’, and the dismissal of André Rivet's works as containing ‘little that was new’ seems somewhat unfair. More generally, the category of ‘Erasmianism’ – so central to much of Dutch (and other) scholarship on seventeenth-century intellectual life – seems rather precarious. Take the case of Claude Saumaise, on whom Nellen has unearthed a wealth of important information. Just like Grotius, he valued a historical approach to the Bible, and saw the Early Church as an ideal. But this never led him to Grotius' irenic dreams. Does this make him less of an ‘Erasmian’? Or is a category that attempts to forge such strong connections between scholarly methods and political aims not inevitably liable to overgeneralisation?

Perhaps another way to consider Grotius' idiosyncrasies, not much explored here, is as a product of his relatively unusual institutional circumstances: seventeenth-century humanist scholars (at least in the Protestant world) tended to be based in universities (one thinks of Scaliger's other students and followers: Heinsius, Saumaise, Drusius, Amama, L'Empereur, etc.). Grotius was in many ways one of the last great ‘sixteenth-century’ humanists, attempting to combine a life in scholarship with one in political service. In this he was similar to another lawyer-scholar, John Selden, recently the subject of a very different but equally brilliant biography by G. J. Toomer (2009) – one would be very interested in Nellen's thoughts on similarities between Grotius and his English counterpart.

This book is for the most part beautifully written and produced. However, given the huge number of subjects that will be of interest to a scholarly audience whose members will not all want to read it cover-to-cover, one might have wished for an index that went beyond proper nouns.