Death of a purist or how Dutch appeared to be a dangerous mother tongue

Camiel Hamans
University of Amsterdam/Adam Mickiewicz University Poznań

27 June 1668, the Amsterdam prosecutor demanded a remarkable punishment: the accused should be displayed on the scaffold, his right thumb should be cut off, his tongue should be pierced with a glowing poker, his books and all his writings should be burned, all his property should be confiscated and he himself should be imprisoned for thirty years. The court, made up of the mayors of the city of Amsterdam, and the public gathered in one of the torture chambers of Amsterdam’s town hall, now the royal palace on Dam Square, must have been shocked. After all, the accused was not a mass murderer, thief, or otherwise known criminal, but an esteemed intellectual, with two doctorates from Leiden University, in both law and medicine, and someone who had friends in the College of Mayors. Moreover, his crime involved a book. Luckily, when the sentence fell, it was only ten years in prison, a huge fine and subsequently ten years in exile. In the end, he served only one of these ten years in captivity. He passed away in prison in the early days of October 1669.


Who was the convict who with his writings had so shaken public order in 17th-century Amsterdam, a city otherwise known for its tolerance? Adriaan Koerbagh (1633–1669)[1] was the son of well-to-do middle-class Amsterdam parents, who studied medicine and law at the universities of Utrecht, Franeker (Fryslan) and Leiden, where he defended his medical dissertation in 1659. Two years later he obtained his doctorate in law at the same university. In Leiden, he and his younger brother Johannes, a student of theology, befriended students who were in contact with Spinoza (1632–1677), who then lived in the nearby village of Rijnsburg. One of the friends was Lodewijk Meyer (1630–1681),[2] who had already published a dictionary of loanwords occurring in Dutch (1654). According to Adriaan Koerbagh’s biographer Leeuwenburgh (2013: 123), Meyer infected Koerbagh with the dictionary virus. Meyer was really close to Spinoza as shown in the preface he wrote for the only book by Spinoza not anonymously published during his lifetime: Renati Des Cartes principiorum philosophiae & Cogitata metaphysica (1663). Another close friend of the Koerbagh brothers was Abraham van Berkel (1639–1686), the later translator of Hobbes Leviathan into Dutch (1667). This group of friends formed the backbone of a Leiden and later Amsterdam-based group of what Jonathan Israel (2001) calls the Dutch ‘Radical Enlightenment’. This, however, did not suffice for prosecution by the Amsterdam authorities.

Early publications

Lodewijk Meyers dictionary Nederlandsche woordenschat ‘Dutch treasure of words’ was a great success. New editions followed one after the other, and he continued to expand the book. In 1663, a third and greatly enlarged edition appeared. A year later Adriaan Koerbagh published with the same publisher: ‘t Nieuw woorden-boek der regten, ofte een veraalinge en uytlegginge van meest alle de Latijnse woorden, en wijse van spreeken, in alle regten en regtsgeleerders boeken en schriften gebruykelijk (The New Dictionary of the Laws, or a translation and interpretation of most all the Latin words, and way of speech, used in all the law books and scriptures of jurists). In his introduction Koerbagh explicitly refers to the works of the famous Dutch lawyers Hugo Grotius and his younger brother Willem. Hugo de Groot explicitly defended the value of his mother tongue Dutch in his youth, as we will see.

It is remarkable that Koerbagh calls his own dictionary ‘Nederlandse Woorden-schat’ several times in his book, suggesting that it is based on or is a sequel to Meyer’s work. Therefore, Leeuwenburgh (2013: 124) calls both lexicons conjoined twins. Also, in his next dictionary, Koerbagh relied heavily on Meyer’s work. The aim of Koerbagh’s first dictionary is twofold: he wants to show that law can be studied and practised in Dutch just as well as in Latin. Consequently, his mother tongue Dutch will be enriched by doing so. Secondly, he wants to present people without knowledge of foreign languages, and especially Latin, the secret language of lawyers, with a tool to understand what barristers and other legal specialist say when they hide behind their learned words. If lay people want to use these foreign words or loans, which he advises them not to do, then they know the meaning of the words they use. Otherwise they would behave as a talking bird that only repeats what it has heard without knowing its meaning.


Koerbagh’s next publication, again a dictionary, appeared to be much more controversial. This 1668 book was entitled Een bloemhof van allerley lieflijkheid sonder verdriet geplant door Vreederijk Waarmond, ondersoeker der waarheyt, tot nut en dienst van al die geen die der nut en dienst uyt trekken wil (A flower garden of all kinds of loveliness, planted without sorrow by Vreederijk Waarmond, investor of the truth, for the benefit and service of all those who want to benefit from it). Even though Koerbagh also used the pseudonym Vreederijk Waarmond – literally ‘Rich in peace Mouth of truth’ – he published this book under his full name. Vandenbossche (1978: 2), one of the earliest philosophers and freethinkers who have dealt with his work, notices that the goal of the Bloemhof is threefold: First of all, it is a criticism of religion, then it seeks to disseminate scientific knowledge, especially Spinozist insights, and finally it offers a catalog of what he considers to be the nice things of bourgeois civilization. Not everyone shares Vandenbossche’s view that Koerbagh and Spinoza do not disagree anywhere, but a description of the similarities and differences between them requires a more detailed study.

Already in one of the first entries of the dictionary Koerbagh cannot resist the urge to express his critical opinion. The entry abdis ‘abbess’ first gives the meaning of the word. Next he goes on to explain that an abbess is a spiritual virgin who has promised to always abstain from sexual relations with men. But at the end of the entry he cannot refrain from voicing his doubts as to whether they in fact stick to their abstention.The entry arke ‘ark’ starts with the literal meaning ‘chest’. Subsequently, Koerbagh refers to Noah’s Ark. Since the dimensions of the Ark are given in the Bible, Koerbach calculates that it must have been impossible to include all the animals and their fodder therein. However, he does not want to blame the author for this failure. Apparently, the person who wrote the story of Noah and the ark did not know any better. He must have heard it said and wrote it down as it was told to him. The implication is clear: here it is not God who is speaking, but a person who was unable to verify the truth.

Koerbagh was particularly interested in loanwords. The word bibel ‘bible’ is such a loanword taken from Greek, where it means ‘book’, just any book ‘even Reynaert the Fox’ or ‘Till Eulenspiegel’. Moreover, the word can refer to a letter. Theologians abuse this loanword and use it for the religious books of the Old and New Testament. Unfortunately, we do not know who the authors of these books are. What we know is that all books of the New Testament are written long after the death of Jesus Christ, whom Koerbach only calls the behouder ‘savior’. His name is never mentioned. Centuries later ecclesiastical gatherings have decreed that these scriptures contain divine truth. Why should not new church meetings now come to a different conclusion?

Incorrect use of a foreign word often leads to misunderstanding, according to Koerbach. For example, in the entry aelemoeseniers armen ‘poor living on alms’, he explains why the loanword aelmoesenier is used here: simply because foreign words can create confusion and obscure the meaning, so that the ignorant can be manipulated with them. Ministers, lawyers and medical doctors love to use learned words to hide the truth or make themselves more important. The Dutch word dominee ‘minister’ offers a nice example: the word comes from Latin dominus ‘master, owner’, or ‘ruler’. However, Dutch ministers wanted to appear somewhat chic in the eyes of the simple farm boys of their congregations. The title ‘spiritual teacher’ was for them not impressive enough, so they chose a Latinized word, dominee, that the congregation did not know and did not understand. The words engel ‘angle’ and duivel ‘devil’ have been introduced in a similar way. Both words come from Greek. Engel originally meant ‘messenger’ in Greek and duivel ‘slanderer’. When the Bible was translated into Dutch the translators deliberately choose not to translate the Greek original words with their Dutch counterparts for ‘messenger’ and ‘slanderer’, boodschapper en lasteraar respectively, but to leave the Greek words in the final Dutch text. Nobody knew what these words meant and what they stood for, so theologians could introduce a new metaphysical and mysterious category of ghosts, which goes back to pagan belief and fears. The fact that ghosts do not exist did not matter. It is a useful category to terrify and oppress ignorant people.

Sometimes Koerbagh is not only critical, but also ridicules the faith of his opponents. When he explains the entry altaar ‘altar’, he starts with the original meaning ‘place of slaughter or sacrifice in a place of worship’ but then he immediately moves to the Roman Catholic liturgy and worship. Roman Catholics are able to do something even God is not able to do: they can produce a human being from a small piece of flour, which, however, also remains flour as it was before. This is of course already impossible according to all laws of nature, but it gets even worse. Subsequently, Roman Catholics feed it to each other, not only as flour but also as man and God at the same time.

Koerbagh does not limit his criticism solely to religion. One example suffices: corpus iuris ‘code of law’.

Dit Rooms wet-boek is een seer groot boek, daar ook veel schoone grollen en onnoodige wetten ten ansien van ons instaan. […] Want men soude in een half soo grooten boek meer wetten, die ons noodiger, en die klaarder en bondiger na de reden waaren, konnen beschrijven in onse eygen taal, als in ’t gantse Roomse wet-boek staan (Koerbagh 1668: 218/9). 
This Roman law book is a very large book, as it also contains many beautiful tricks and unnecessary laws regarding us. […] For one could describe in a half the size of a book in our own language more laws which are more needful to us and are clearer and more concise according to reason than in the entire Roman law book.

Unsurprisingly, the publication of this book caused a stir. Orthodox Reformed ministers in particular became very angry and turned to the College of Mayors. They called on Koerbagh to explain himself. He did not answer the summons but instead fled Amsterdam.

A Light

While in hiding, he worked on another book to provide the theoretical underpinnings of his philosophy and theology. This work, een Ligt schijnende in duystere Plaatsen, om te verligten de voornaamse taaken der Godsgeleerdheyd en Godsdienst, ontsteeken door Vreederijk Waarmond, onderzoeker der Waerheyd (A light shining in dark Places, to illuminate the main questions of Theology and Religion, kindled by Vreederijk Waarmond, researcher of the Truth)[3] was on the printing press when the printer began to suspect that it might contain forbidden heterodox material.[4] Even though Koerbagh’s brother and Van Berkel tried to convince the printer with an amount of money to continue the printing, he stopped it and  handed over all printed sheets to the Utrecht municipal authorities, who contacted their Amsterdam colleagues. An arrest warrant was issued and thanks to the well-paid betrayal of a former friend, Koerbagh was found and arrested in Leiden. The Amsterdam court wanted to have access to the full text of the possibly blasphemous Ligt and therefore had the sheets bound along with the handwritten manuscript of the as yet unprinted portions of the book. Each member of the court received a copy. So it is that there are still two copies of a book that was never published in 1668.

Koerbagh’s case was brought to trial and despite his good relations with a number of Amsterdam mayors, he was convicted, an outcome that is quite exceptional. The reason for this should be sought less in the deviant ideas that Koerbagh presented than in the fact that he did this in his native language Dutch, so that every literate inhabitant of Amsterdam – and there were many more than one would suppose – could become acquainted with his inflammatory, radical ideas. Lodewijk Meyer, for instance, anonymously published a radical book in Latin in 1666 that caused much commotion but never led to a lawsuit, even the Dutch translation published a year later did not.

Of course, there is a huge difference between Meyer’s anonymously published work and Koerbach’s overt provocations. However, the main difference is the aim of the publications. Koerbagh explicitly defends his choice for his mother tongue so that he could reach a wider audience than just Latinized scholars. However, incitement was not his main goal. He wanted to give his fellow citizens an opportunity to think and discover the truth. Dutch was ideally suited for this.   

Dutch purist tradition

In the introduction to the Bloemhof Koerbagh complains that the ancient Greeks had such an enormous advantage over other peoples, such as the Dutch of his day. The Greeks did not have to spend years learning a foreign language. They could immediately start practicing arts and sciences. That is why they reached such great heights in knowledge and understanding. Other peoples lose years before they can get to real science, and that counts especially when it comes to the practice of mathematics, for it is the foundation of all arts and sciences and an important tool for sharpening reason and judgment. How much extra time we Dutch could gain to find hidden causes and to increase our knowledge, if we did not first have to master a foreign language before being able to engage in arts and science. Especially, since

onse eygen taal, dewelke ik agte de heerlijkste, rijkste, en beduytsaamste taal der waereld te sijn
‘our own language, which in my opinion is the most glorious, richest, and most meaningful language of the world’ (Koerbagh 1668: *2v)

That a people’s own language is the best, the richest and the most beautiful language was, and maybe still is, a popular prejudice among speakers of European languages from the 15th and 16th century on. However, that it was the most meaningful language is a special feature of the Dutch, and German, tradition in thinking about language.[5] It all started with the notorious Becanus (1519–1572) and remained alive up to and including Schotellius (1612–1676), the founding father of German study of grammar.

As is well known, Becanus claimed that Dutch was the language of Paradise. Thus, the true knowledge given by God to mankind was contained in the words of Dutch. Especially since it consisted of so many monosyllabic words, Dutch should not be far from true knowledge. Anyway, true knowledge must be simple and thus be expressed by simple words. Another argument for the exceptional character of Dutch was the ability to compose monosyllabic words into compounds. In this way simple ideas could be combined to form complex concepts.

Becanus was not alone in his thinking. The first Dutch grammar Twe-spraack vande Nederduitse letterkunst (1584) (Dialogue on the Low German [Dutch] grammar) also held a similar opinion regarding the richness of monosyllabic words and the ease of compounding. Simon Stevin (1548–1620), a Flemish engineer who initiated a Dutch-speaking course of training in engineering in Leiden – the so-called Duytsche Mathematique (Dutch Mathematics) – on behalf of Prince Maurits of Oranje-Nassau, the army leader in the fight against Spain, held similar views. He did not claim that Dutch was the language of Adam and Eve, but he thought that there had been a Wijsentyt ‘Period of the wise men’, a period more or less similar to Hesiod’s ‘Golden Age’. According to Stevin, this is the time in the history of mankind in which man received wisdom and language at the same time. Thus, true knowledge must have been expressed by the original language. Again, the number of monosyllabic words and the ease of compounding were arguments in defense of the primacy of Dutch. Of course, Dutch had been corrupted over time. So, one had to restore the original forms and especially one had to remove loanwords from this ideal language, since they obscured understanding of and insight into the true nature of things. That is why Steven introduced Dutch equivalents for Latin terms in the disciplines he dealt with. Mathematics became wiskunde from the verb (be)wijzen ‘to prove’ and kunde ‘science’. Tangent was translated and ‘enlightened’ by the term raaklijn, ‘a line that touches somewhere’, etcetera. Most of his terms are still in daily use. His pursuit has been taken over by others. That is why in Dutch grammars one still finds Dutch terms such as lijdend voorwerp ‘suffering object’ for direct object or gezegde ‘what has been said’ for predicate.

As is clear, the success of Stevin heavily influenced the debate about the status of Dutch. A well-known specialist in law like Hugo Grotius (1583–1645) – who was not only a lawyer but had in fact started his career as a classicist, and who was friends with Stevin through his father – argued in a work from his youth that language, and in particular Dutch, is a representation of reality and that language analysis thus provides insight into the real nature of the world. Due to de Groot and his followers, Dutch legal language contains a lot of internationally idiosyncratic Dutch terms. The famous Dutch poet, historian, judge, and administrator Pieter Cornelisz. Hooft (1581–1647) followed suit and tried – albeit unsuccessfully – to introduce the Dutch term vernufteling ‘someone who works with ingenuity’ for engineer. Even though this coinage never found widespread adoption, the most prestigious modern price for Dutch engineers is still called ‘De Vernufteling’.

This purist tradition did not stop with Grotius and Hooft, nor even at the Dutch border. The great German grammarian Schottelius (1612–1676) borrowed many of his opinions from Stevin. He even agreed with Stevin with respect to the fusei character of (Dutch and) German:

Die teutsche Sprache, welche die tieffe Verborgenheit der Natur gründlich ausbilden kann
‘the German/Dutch language which can really depict what is deeply hidden in nature’ (Kiedron 1985: 251).


Koerbagh was not only a strong and vocal proponent of new radical, philosophical ideas, such as those advanced in Spinozism and other forms of the Radical Enlightenment, he was equally rooted in a purist Dutch tradition. That is why he not only tried to market his ideas in Dutch, but also at the same time tried to convert terms and concepts that were shrouded in an obscuring shell of foreign language into clear Dutch. What had hitherto been hidden from the view of the ignorant by the alien appearance of a quasi-learned terminology, now suddenly came into view, revealing that the emperor was wearing no clothes. This caused him to be convicted in the otherwise tolerant 17th century Amsterdam.


Bossers, Anton (1986). Nil volentibus arduum: Lodewijk Meyer en Adriaan Koerbach. P.A. Tichelaar (ed.). Opstellen over de Koninklijke Bibliotheek en andere studies. Hilversum: Verloren: 374-383.

Hamans, Camiel (subm.). Goropius Becanus in gevecht met de geschiedenis. Submitted to Rocznicki Humanistyczne, Annals of Arts, Annales de Lettres et Sciences Humaines.

Israel, Jonathan L. (2001). Radical Enlightenment. Philosophy and the Making of Modernity 1650-1750. Oxford: Oxford University Press.

Kiedron, Stefan (1985), Taalkundige opvattingen van Simon Stevin en hun weerspiegeling in de “Ausführliche Arbeit von der Teutschen Haubt-Sprache van Justus Georg Schottel”. Neerlandica Wratislaviensia II: 241-271.

Koerbagh, Adriaan (1664). ’t Nieuw woorden-boek der regten ofte Eene vertaalinge en uitlegginge van meest alle de Latijnse woorden, en wijse van spreeken, in alle regten en regtsgeleerders boeken en schriften gebruykelijk. Amsterdam: Weduwe van Jan Hendriksz Boom. Also available at:

Koerbagh, Adriaan (1668). Een bloemhof van allerley lieflijkheyd sonder verdriet geplant door Vreederijk Waarmond, ondersoeker der waarheyd, tot nut en dienst van al die geen die der nut en dienst uyt trekken wil. Amsterdam: published by the author. Also available at:

Koerbagh, Adriaan (2011). A Light Shining in Dark Places, to Illuminate the Main Questions of Theology and Religion. Edited and translated by Michiel Wielema. With an introduction by Wiep van Bunge. Leiden/Boston: Brill.

Koerbagh, Adriaan (2014). Een licht dat schijnt in duistere plaatsen. Hertaling Michiel Wielema. Nijmegen: Van Tilt.

Laurens, Hannah (2019). De rede: bron van geluk voor iedereen. Inleiding tot de filosofie van Adriaan Koerbagh 1633-1669. Nijmegen: Van Tilt.

Leeuwenburgh, Bart (2013). Het noodlot van een ketter. Adriaan Koerbagh 1633-1669. Nijmegen: Van Tilt.

Meinsma, Koenraad O. (1896, 1980²) Spinoza en zijn kring. Historisch-kritische studiën over Hollandsche vrijgeesten. ’s-Gravenhage: Nijhoff/ Utrecht: HES.

Schuyt, Kees (2017). Spinoza en de vreugde van het inzicht. Amsterdam: Balans.

Vandenbossche, Hubert (1978). Adriaan Koerbagh en Spinoza. Leiden: Brill. Mededelingen vanwege het Spinozahuis XXXIX

Van Hardeveld, Ike (2000). Lodewijk Meyer (1629-1681) als lexicograaf. PhD-thesis University Leiden. Available at:

Van Moerkerken, Pieter H. (1948). Adriaan Koerbach. Een strijder voor het vrije denken. Amsterdam: Van Oorschot. De Vrije Bladen.


[1] A modern biography of Koerbagh is Leeuwenburgh (2013), Meinsma (1896, 1980²) was the first to draw attention to Koerbagh, Van Moerkerken (1948) is an attempt at rehabilitation. Israel (2001) not only provides a short biography of the two brothers Koerbagh but also assigns them a central place in the early Dutch Radical Enlightenment. A short introduction to the philosophy of Koerbagh is Laurens (2019).

[2] For more details about Meyer and his contacts with the Koerbagh brothers, see Bossers (1986) and Van Hardeveld (2000).

[3] An English edition and translation is Koerbagh (2011). A modern Dutch translation is Koerbagh (2014)

[4] Schuyt (2017: 540 was able to demonstrate that Koerbagh must have had access to an unpublished manuscript of Spinoza when writing his Ligt. This manuscript is the Korte Verhandeling van God, de Mensch en deszelven Welstand (+/- 1662) (Short Treatise on God, Man and his Well-being). Koerbagh’s discussion of God and his onder-standigheid ‘sub-stance’ owes a lot to Spinoza. However, Koerbagh does not accept the term sub-stantia ‘sub-stance’. He prefers ip-stantia ‘ip-stance’, since sub means ‘under’. Thus, ‘substance’ suggests a dependence where ip(se) ‘self’ in ipstantia makes clear that the word means ‘independence’ or in Dutch zelfstandigheid. Meyer (1666) also made use of Spinoza (1662).

[5] For a short overview of this Dutch, and German, tradition, see Hamans (subm.)

How to cite this post

Hamans, Camiel. 2020. Death of a purist or how Dutch appeared to be a dangerous mother tongue. History and Philosophy of the Language Sciences.

Posted in 17th century, Article, History, Netherlands

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