The Calvinist Copernicans

History of Science and Scholarship in the Netherlands, volume "

The series History of Science and Scholarship in the Netherlands presents studies on a
variety of subjects in the history of science, scholarship and academic institutions in the Netherlands.
Titles in this series
". Rienk Vermij, The Calvinist Copernicans. The reception of the new astronomy in the
Dutch Republic, "^". , isbn ---
. Gerhard Wiesenfeldt, Leerer Raum in Minervas Haus. Experimentelle Naturlehre an der Universita t Leiden, "^"". , isbn ---
. Rina Knoeff, Herman Boerhaave ("^"). Calvinist chemist and physician.
, isbn ---
. Johanna Levelt Sengers, How fluids unmix. Discoveries by the School of Van der
Waals and Kamerlingh Onnes. , isbn ---
Editorial Board
K. van Berkel, University of Groningen
W.Th.M. Frijhoff, Free University of Amsterdam
A. van Helden, Utrecht University
W.E. Krul, University of Groningen
A. de Swaan, Amsterdam School of Sociological Research
R.P.W. Visser, Utrecht University

The Calvinist Copernicans

The reception of the new astronomy
in the Dutch Republic, "-"
Rienk Vermij

Koninklijke Nederlandse Akademie van Wetenschappen, Amsterdam

 Royal Netherlands Academy of Arts and Sciences

No part of this publication may be reproduced, stored in a retrieval system or
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edita@bureau.knaw.nl, www.knaw.nl/edita
isbn ---
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The paper in this publication meets the requirements of *
(") for permanence

The investigations were supported by the Foundation for Historical Research, which is subsidized by the Netherlands Organization for Scientific
Research (nwo)

Contents

Acknowledgements viii
Introduction "
part i. a world of order

". The context of learning ""

A bourgeois society ""
Leiden university: general "
Mathematics and the humanist program "
. Cosmography and classical studies
Leiden professors and the system of the world
Ancient precedence
Cosmic harmony: the Capellan system

. Humanist mathematicians and Copernicus

Willebrord Snellius
Nicolaus Mulerius
. Simon Stevin and the tradition of practical mathematics
Mathematical practitioners and the system of the world
Simon Stevin, a mathematician with pretentions
Stevin's astronomy
Stevins' Copernicanism
Willem Jansz Blaeu
. Philips Lansbergen's Christian cosmology
Life and work
Lansbergen's Copernicanism
Lansbergen's Christian cosmology
Alchemy and the motion of the earth

contents

part ii. the challenge to philosophy

""

. Thinking the cosmos after "" "

Dissemination of the debate "
Attempts at a new cosmology """
. Astronomy at the universities "
Tychonians "
Copernicans "
Philosophers "
part iii. the universe of law

"

. Cartesian cosmology "

A physics of the universe "
Daniel Lipstorp: mathematics as philosophy "
Christophorus Wittichius' decisive argument "
Out of Descartes: Christiaan Huygens "
New theories of motion "
. Cartesian cosmology at the Dutch universities "
A new program of learning "
Resistance to the Cartesian world-view "
The first conflicts on Cartesianism at the Dutch universities "
Aftermath of the conflicts "
Academic discussion on the system of the world in the second half of the
seventeenth century "
Conclusion: character of the debate "
". The impact of Cartesianism outside the universities "
Intellectual life in the second half of the seventeenth century "
The mathematical practitioners "
Popular discussions on Copernicanism
Surpassing Descartes "
The impact of the new astronomy: poetry "
The testimony of world maps
part iv. biblical authority and christian freedom: copernicanism
and bible interpretation
"". Copernicanism in the theological discussion. Preliminaries to a problem "
The Bible in Reformed theology "
Early theological positions on Copernicanism
Cartesianism enters the fray "

vi

contents

". Copernicanism as a theological problem: the Wittich affair

A theologian championing Copernicanism
Detractors and rejoinders
Some other voices

". Copernicanism as a political problem: The Velthuysen affair

Voetianism as a political program
Lambert van Velthuysen and the struggle with Voetianism at Utrecht
The controversy on Copernicanism and beyond "
Related polemics in "
A belated echo
". The schism within the Dutch Reformed Church
A Voetian counter-offensive
Wittich and the synod of Gelderland
Preparing the South Holland synod
The decree against Cartesianism and its aftermath
Building a Cartesian faction "
The dispute in a wider setting "
Theologians on the system of the world after "
part v. god back in nature: copernicanism in the 18th century

". Newton's theories and Copernicanism at the Dutch universities

Leiden: the transformation of natural philosophy
Leiden professors in defence of Copernicus
Copernicanism and anti-Copernicanism at Utrecht university
". New tendencies in theological and apologetic thinking
Jean Le Clerc's reception of the Principia
Bernard Nieuwentijt and Dutch physico-theology
The end of the theological strife
". The cosmological debate in society at large
A fashion for astronomy
Some final skirmishes

General conclusion
Abbreviations
Bibliography
Index

contents

vii

Acknowledgements

The debts I have to acknowledge in presenting this work are manifold. In the
first place, I am happy to say thanks to Klaas van Berkel of Groningen University, who initiated the whole project and remained a firm supporter and
valuable critic throughout. I should also like to thank the other directors of
the project `Culture in the Dutch Republic', in particular A. Th. van Deursen
and S. Groenveld, who adopted my work within their overall project. I also
thank the other members ^ directors and researchers alike ^ of this project for
their support and comments. nwo, which provided the funding, deserves
special mention.
Several other people helped me a great deal by reading and commenting on
my text, or parts of it, as it developed. At Groningen, I found a very interested and enthusiastic colleague in Eric Jorink, who read and commented on
all my chapters. Most contacts, however, were abroad or spread across the
whole country. Floris Cohen was willing to read my work and provide valuable feedback. I also owe much to the encouragement and expertise of Moti
Feingold. At a later stage, Albert van Helden offered much support. A person
engaged in closely related studies was Wiep van Bunge. I owe him thanks,
both because he was prepared to read my work and because he was willing
to show me his. Equally, Theo Verbeek was always very helpful in putting his
enormous knowledge on Cartesianism at my disposal. I owe many thanks to
Willem van Asselt for his expert comments on my views on the Voetian-Cocceian debate, although I am afraid that on some points he did not convince
me. Marc Wingens was willing to share his knowledge of early modern Dutch
universities and university professors with me, and Charles van de Heuvel
read a version of my chapter on Stevin. Many other people answered questions or gave hints on various aspects of my work.
I carried out this research mainly while working at Groningen University.
Nevertheless, I was glad to find that I was still welcome at the Utrecht Institute for the History of Science, where I could use the splendid library and
where my former colleagues Bert Theunissen, Frans van Lunteren, Lodewijk
Palm, Kees de Pater, Rob Visser and others were always very supportive and

viii

acknowledgements

helpful. At a later stage, a fellowship at the Herzog August Library in Wolfenbuttel proved very useful for finishing the work off (although, in fact, I
went there for other reasons). I owe quite a lot to the Library's generous support, and to discussions with the other fellows. I am glad that Maastricht
University, where I am presently engaged, offered me the opportunity to finish the project.
I now come to a very special debt. The late Professor R. Hooykaas studied
the reception of Copernicanism in the Netherlands several years before I
started my study. His investigations resulted in several publications, the best
known of which is his edition of Rheticus' treatise on the Bible and the motion of the earth ^ a treatise believed to be lost until Hooykaas identified a
copy. However, his death in " left the larger project unfinished and unpublished. I owe much gratitude to Professor Hooykaas' widow, as well as to
Floris Cohen, the curator of his papers, for allowing me to study the relevant
manuscripts at my leisure. It certainly was of much help to become acquainted
with the views of such a renowned scholar and eager student of the subject.
Here and there, the reader will find in the notes references to Hooykaas' papers.
Hooykaas' papers have by now been transferred to the State Archives in
Haarlem. In time, they will be accessible for scholarly research. Inevitably,
there are differences between his approach and my approach. Hooykaas starts
right away in " and pays much attention to some early reactions to Copernicus' work from mathematicians living in, or originating from, the territory
which later would be the Dutch Republic. In some cases, this concerns detailed investigations which perhaps will be published some day. I have left out
this episode altogether and start only with the beginnings of the present
Dutch state and the foundation of Leiden University in ". On the other
hand, Hooykaas pays little attention to events after ", not to speak of the
eighteenth century. He also pays little attention to the debates on Cartesianism and the ecclesiastical strife, although he does deal with some individual
authors, such as Van Nierop and Velthuizen. As will be seen, in my own book
this later period takes a central place. Still, this leaves a considerable overlap
between his work and mine. Authors like Mulerius, Lansbergen and Blaeu
take a prominent place in any case. (For some reason, Stevin is not dealt
with in the papers I saw.)
Finally, anybody looking through the references will realise how much I
owe to the staff of the various archives and libraries both at home and abroad.
These people will have to remain unmentioned here ^ in most cases, I do not
even know their names ^ but it would be very inattentive to omit them completely.

acknowledgements

ix

Some final remarks on names and dates. As for dates, the reader should be
alert that during the greater part of the period under review, two different
calendars were in use in the Dutch Republic. The provinces of Holland and
Zealand adopted the Gregorian calendar as early as " January ", whereas the
other provinces (Groningen, Friesland, Overijssel, Gelderland and Utrecht)
stuck to the Julian calendar until "-"". Seventeenth-century names are
notoriously capricious in their orthography. Moreover, many scholars latinised
their names. There seems to be no consistent way to deal with this. As a rule, I
opted for the version under which the person in question appeared to be best
known in English. Persons indicated by a latinised name are introduced with
their real names.
In Dutch names, prefixes like de, van, etc. are not capitalised. However, this
rule can be superseded by another rule, which says that all names, in the form
they are written down, must begin with a capital letter. So, one writes Simon
van der Moolen, but if one omits the first name, this becomes Van der Moolen.
I have followed the Dutch convention throughout this book, except in the
references in the notes, as a reminder that the prefixes do not count in the
alphabetical order. Patronyms were frequently used in the seventeeth century,
usually in an abbreviated form. One writes Jansz. or Pietersz. for Janszoon
(`son of Jan') or Pieterszoon (`son of Pieter'). Here, the full stop serves as an
abbreviation mark. In order not to confuse the foreign reader, I omitted it in
the text.

acknowledgements

Introduction

Writing about the history of the Copernican theory may or may not appear to
need special justification. It does not need it in that the subject is of acknowledged relevance in the history of science, and it does need it in that one
should explain what one can still hope to contribute to a subject already dealt
with quite elaborately in the literature. The question I am posing is not really
new, viz. why and how did Copernicanism turn into a received and established scientific theory? Nor do I claim much originality for my method,
which comes mainly down to studying the discussions on the system of the
world in a given context over a longer stretch of time. My justification lies in
scope rather than in a new approach to a particular well-known person or
episode.
The context I deal with is the Dutch Republic. There are several reasons for
this. For one thing, although the Republic was rather small ^ small enough
for a single researcher to overview it ^ its place in Europe in the seventeenth
century was certainly not insignificant. Its universities were famous and drew
students from all over Europe. Science had advanced a long way and produced some outstanding scholars. The importance of the United Provinces
vis-a -vis science has long been recognised by the international community
of historians of science, and some fine studies on the issue have been published. However, there are only some smaller studies on the reception of the
new astronomy. " What makes the United Provinces a particularly useful case
is the fact that state interference with intellectual developments was minimal,
though not absent. There was a lively intellectual debate involving many parties. New developments, such as Cartesian philosophy, found an early audience here. Moreover, as a nominal Protestant country with a largely secularised government, it offers a setting in which Copernicanism has been
little studied.
"

For a textbook on the history of science in the Netherlands, see van Berkel, Palm and van Helden ("). On the history of Copernicanism in the Netherlands, see Vermij ("); Hooykaas
("); Snelders ("); de Smet (").

introduction

"

Strictly speaking, the `reception' of Copernicanism is an ugly term: it implies a passive attitude on the part of the receiver, who can simply accept or
reject the theory offered. Of course, this is hardly ever the case. Ideas are not
inert, inflexible objects which can only be passed on. They are created,
adapted, transformed and interpreted; their meanings change; people realise
new consequences, combine them with other ideas and discover new applications. Nowhere this is clearer than in the history of Copernicanism. The `new
astronomy' was not suddenly discovered by Copernicus; modern ideas on the
solar system were the result of a long and fateful debate, wherein the work of
Copernicus was only one, be it a very crucial, stage.
It is common nowadays to speak of the `new' astronomy of Copernicus and
his followers, as opposed to the `old' astronomy of Ptolemy and the Medieval
period. However, it took a long time before such a dichotomy became clear.
True, Copernicus himself had presented his book De revolutionibus as a new
Almagest, an emulation of the astronomy of Ptolemy. Henceforth, there
were two full-fledged astronomies and two views on the constitution of the
universe, both of which were supported by astronomical calculations and astronomical authority. Although this stirred interest in astronomy and cosmological speculation, it did not mean that people were forced to choose between the two. Initially, rather than simply choosing between two complete
systems, people framed their own ideas, combining existing theories and
picking from either theory the elements which suited them. Indeed, Mulerius
spoke as early as "" of two `sects' in astronomy, the peripatetics and the
Pythagoreans, as he called them. But his own case clearly illustrates that astronomers were not sectarians. They did not side for or against Copernicus,
but for or against certain elements in his (or Ptolemy's) work. The debate
centred on technical details, not on the systems as such. Before one can speak
of `the reception of Copernicanism', on should ask how, in the wake of Copernicus' work, such a clear-cut `Copernicanism' came into being at all.
As will be seen, a clear dichotomy between a `new' and an `old' astronomy
developed only in the course of the seventeenth century. However, by that
time the dichotomy was not so much between the astronomical systems
themselves, as between rivalling systems of natural philosophy. The `new astronomy' became part of a `new physics'. Ideas on the world system were only
a part of these ^ and, as it turned out, a symbol. The major theme in the

It is impossible to mention here all titles on the subject. Elementary works on the history of
astronomical theory are Dreyer (") and Kuhn ("). On the reaction to Copernicus' work, see
for instance North ("), Baumgartner (") and the various works by Westman. For the reception of the new astronomy in different national contexts, see Reception.

Mulerius ("") preface: `Duas hodie esse Astronomorum sectas in confesso esse.'

introduction

history of Copernicanism is the transition of Copernicanism from an astronomical theory ^ which mainly gave rise to technical discussions among specialists ^ to a constitutive element of a completely new, physical world-view.
For this reason, historians studying the discussions on the new astronomy
have concentrated on the interaction between mathematical and physical arguments. It is this interaction which gave the heliocentric theory its impact
and turned its `reception' into one of the main episodes of the scientific revolution.
This is a complicated affair, as the views on what mathematics and physics
entailed have changed over the course of time. Clearly, `Copernicanism' is a
theory on the constitution of the solar system. It is not a mathematical device
for calculating planetary and stellar positions, although such devices made up
by far the greater part of Copernicus' book. It is not uncommon to make in
the early reception of Copernicus' work a distinction between a `physical' and
a `mathematical' interpretation. Whereas Copernicus intended his heliocentric
model to be a representation of reality, most early readers took it as a convenient mathematical model which was helpful for astronomical calculations.
There is no doubt that many readers refused to accept Copernicus' heliocentric theory as a description of reality. But it is important to be aware that
the distinction between a description of reality and a mathematical device is
not the same as the difference between a `mathematical' and a `physical' theory,
as these concepts were seen at the time.
Here it may be useful to point out that, in Copernicus' time, there was a
well-established division of astronomy into astronomy proper and cosmography. Whereas the former taught the calculatory devices by means of which
stellar positions could be calculated, the latter comprised the description of
the universe ^ the various celestial spheres, their positions and their periods of
revolution. Cosmography was definitely a part of mathematics. In the Middle
Ages, it was generally taught from Sacrobosco's treatise De Sphaera. This was
a very elementary book which did not contain any calculations. Sacrobosco's
book remained popular in the sixteenth century. Various updated editions
appeared. The best known was the one edited by Christophorus Clavius, the
papal mathematician. But by this time, many new works had been written,
attesting to the interest the subject elicited. The authors were invariably mathematicians. A new standard was set by Petrus Apianus in his Cosmographicus
liber ("), in which he integrated astronomy and geography: the description
of the universe comprehended both the system of the world ^ from the fixed
stars and the planets down to the earth ^ and the description of the earth

Thorndike (").

introduction

itself, with its mountains and seas, countries and cities. This model was imitated by many. Apianus' book became particularly well known in the adaptation by Gemma Frisius], from Louvain. Other popular cosmographies from
the period were the Protomathesis (") by the Paris mathematician Oronce
Fine, Elementa doctrinae de circulis coelestibus, et primu motu ("") by the Wittenberg
mathematician Caspar Peucer, and Novae questiones sphaerae, hoc est, de circulis coelestibus, et primo mobili (") by Sebastian Theodoricus, who was also from
Wittenberg.
Both astronomy proper and cosmography were part of mathematics. But
whereas the ontological status of the theories of astronomy proper was doubtful, in the case of cosmography there were no such doubts. The description of
the world as offered by cosmography should simply represent reality. This
description was not `physical' as contemporaries understood the term. If one
were to define sixteenth-century natural philosophy according to its subject
matter (one might also defend that it was the discipline which explained Aristotle's libri naturales), one would call it the science of qualities and causes. It was
certainly not the description of reality: that was left to more humble disciplines
such as natural history or mathematics. Natural philosophers were concerned
with what was behind reality; their task was not to describe but to explain it.
Their main problem, with hindsight, is that they regarded reality as basically
unproblematic and `given'. As such, philosophy was strictly speaking not
equipped to choose between alternative descriptions of reality.
This does not negate the fact that a person's view of the universe was
founded in that person's idea of reality in general. In his unpublished work,
Hooykaas looked at this problem in an interesting way, viz. by investigating
the different ways scholars have represented the cosmos by models. On the
one hand, people built purely mechanical models such as Blaeu's tellurium, on
which Hooykaas collected a lot of documentation. Another example is the
model made by Adriaen Anthonisz and described by Mulerius. On the other
hand, there are the alchemical experiments by Cornelis Drebbel, which represent the motion of the earth as an animated, organic process. The latter model, for instance, turns up in the work of Lansbergen. By focussing on such
modelling, Hooykaas links the ideas on the system of the world to the general
philosophical view of nature.
I have chosen a different approach by concentrating on the way cosmography became part of an established philosophical-physical discourse. Contemporaries clearly regarded the natural philosophy of their time as wanting in
explanatory power regarding the many new discoveries made during the six

On sixteenth-century cosmographical literature: Thiele (").

introduction

teenth and seventeenth centuries. Galileo's telescopic discoveries in particular

demonstrated the shortcomings of the old philosophy. Many independent
thinkers sought a new philosophy of nature. By the middle of the seventeenth
century, the heliocentric theory was an important touchstone for any philosophical system. Hence, `Copernicanism' could become an important element
in the philosophical debates of the time.
The relative importance of and the interaction between physical and mathematical arguments in the discussions on the Copernican theories are a main
theme of the first three parts of this book. Part i presents a study of the first
reception of Copernicus' ideas in the Dutch Republic. Various elements from
Copernicus' work drew a lot of interest, and his theories certainly affected
cosmological thinking. But only a few people openly adopted his central thesis of a moving earth and a central sun. Official scholarship saw too many
obstacles. Only people on the fringe of the learned world were ready to
draw the more radical conclusions from Copernicus' work. All participants
in the debate agree that the importance of Copernicus' theory is in its description of reality. No one tries to neutralise its effects by reducing it to a calculatory device. At the same time, philosophical arguments are completely absent. A description of reality is sought by mathematics only.
Part ii focuses on the impact of Galileo's telescopic discoveries. It is now
commonly accepted that it was these discoveries which turned the Copernican
hypotheses from an esoteric doctrine, defended by only a few specialists, into
a serious alternative to the traditional world-view. My investigations amply
confirm this. The telescope made people look at the heavens with, almost
literally, a different eye. Not just the celestial motions but the very nature of
the heavens became a matter of investigation and speculation. Mathematical
arguments receded into the background. The constitution of the universe became the subject of a lot of physical speculation. Such speculation is unconnected with traditional philosophical arguments. Among its first proponents
are people without any formal mathematical or philosophical education. At
universities, the teachers of physics only slowly became aware of the relevance
of the new astronomical discoveries.
In Part iii, the focus is on the apotheosis of the new approach in the philosophy of Rene Descartes. In Descartes' philosophy, heliocentric cosmography is a central element, but it is no longer treated in a mathematical way.
Cosmography is by now the domain of natural philosophers with often the
haziest idea of mathematics and astronomy. In this climate, `Copernicanism'
became a definite and recognisable concept. The earlier mathematicians concocted their own systems. The natural philosophers after " simply lacked
the competence to deal so freely with mathematical data. They preferred the

introduction

Copernican world system not because of its astronomical merits or demerits,

but because of their adherence to a general philosophy of nature.
The emergence of clear `Copernican' and `anti-Copernican' camps is thus
partly explained by the role the world system plays in more comprehensive
debates. The debate is no longer about the details of the various solutions to
the problem of the constitution of the universe. The respective world systems
are so to speak the battle cries or the banners in a debate between competing
philosophical schools. One might of course go further and ask why this philosophical debate, unlike the earlier cosmographical debate, became polarised
in this way ^ though perhaps `polarised' is too strong a word here, as matters
were not entirely black and white. Here, one encounters the religious element, which enters in the wake of the philosophical argument. The hardening
of the frontiers in the philosophical, and hence cosmographical, debate in the
last resort originates in theological oppositions.
Religion is in effect a second main theme in the history of Copernicanism.
The religious controversies accompanying the debate on Copernicanism have
for a long time been a main point of attention of historians of science. So far,
however, this attention has been unevenly distributed: most has been paid to
the reactions within the Roman Catholic Church in general and to the trial of
Galileo in particular, and very little has been written on the situation in the
Protestant churches. The ideas of individual Protestant thinkers are generally
known and some nice work has been done on a few topics, such as the reception of Copernicus' ideas at the Lutheran university of Wittenberg in the sixteenth century. But a detailed study of events in the Dutch Republic, which
was officially a Protestant country (although it tolerated large groups of dissenters within its borders) should offer a major contribution to the international literature on the subject. The vehement debates which were waged
within the Dutch Reformed Church, especially during the second half of
the seventeenth century ^ debates which were widely known at the time and
quite influential in the Protestant world ^ have so far received only scant attention in the international literature on history of science.
Of course, one might well ask why these theological debates should be
much more polarised than the discussions between astronomers or philosophers. The point is, of course, that it would be far too simple to regard these
theological debates as just that ^ the uncommitted and uninterested speculations of individual theologians. Indeed, in recent years historians of science
have increasingly come to realise that the religious controversies surrounding
the introduction of the new science are in fact often politically rather than
religiously motivated. Jacob's work on Boyle and the English Revolution,
Shapin and Schaffer's work on the controversy between Boyle and Hobbes,
and Redondi's and Bagioli's work on Galileo are cases in point. In the Dutch

introduction

case, too, the furious debates on the system of Copernicus and the philosophy
of Descartes become understandable only within their politico-social context.
It was not a case of two parties disagreeing about the new philosophy or their
exegetical principles, but of two parties competing for power. Very pointedly,
one might say that they were not quarrelling because they had a disagreement, but that they created a disagreement because they had a quarrel. This
makes the religious issue both far more complicated and far more interesting
than a private dispute between theologians. In Part iv, these developments
are explained in some detail.
With some exaggeration, one could say that we can speak of a `reception' of
the idea only after ", when Copernicanism had become a clear-cut concept,
i.e. one which was a given rather than asking to be defined. It then became a
matter of gaining more adherents and dealing with the common objections.
Of course, this cannot be isolated from the religious and political relations.
The dissemination of the Copernican system in the Dutch Republic implied
the undoing of the religious sensibilities concerning the subject which had
built up in the foregoing period. This was facilitated on the one hand by
the calming down of the political opposition, and on the other by the demise
of Cartesian philosophy, which in the eyes of many had been too compromised. Copernicanism remained an element in a general physical worldview, but from now on this was based on the theories of Newton, which
gave much less offence. This development will be explained in Part v.
I should point out that, although the story is ordered chronologically and
divided by some important points, I do not always follow the exact sequel of
events. The division is by generations rather than events. That is, I take it that
people are formed in their youth and early adulthood, and generally are little
affected by new developments after that time. For instance, Lansbergen's
main publications appeared about two decades after Galileo's telescopic discoveries, which were published in "". Still, in the order of argument Lansbergen's work comes before Galileo's discoveries, as Lansbergen was born in
"", had his ideas formed before Galileo appeared on the scene, and in his
work shows hardly any awareness of the new discoveries. In a similar manner,
Beeckman, Hortensius, and Holwarda are treated as pre-Cartesian philosophers, although Beeckman and Hortensius knew Descartes personally, and
Holwarda was over years his junior.

introduction