scholars such as ‘s Gravesande, Musschenbroek, or van Marum’s contemporary Jan Hendrik
van Swinden.
As for the first point, the clearest statements on this matter stem from the early phase of his
career, and in them he emphasises the importance of experiments. From what amounts to a
summary of his view of the history of science which he gave during a lecture in July 1777, it
clearly transpires how van Marum situated his activities within the tradition of what later
came to be labelled as the “Scientific Revolution”.124 He granted that “entirely correctly [...]
the ancient Greeks [may] be viewed as the true founding fathers of several sciences”, yet he
lamented that all their theories were no more than mere assumptions, adding: “testing them
with special experiments, was not the fashion of that time”. He then pointed out how
Aristotle’s “propositions” had above all been indisputable, but only “until finally in the
preceding Century Man began to question Nature with the help of experiments.” According to
van Marum, this was a watershed. He describes the impact thus (in a handwritten note that is
partially indecipherable, but the gist of which is readily understandable):
“Erelong it was seen that the Propositions of the Scholastic Philosophers, which had been
taught so long and had been so much extolled, were pure fabrications; and discoveries were
made that shed much light on many phenomena and that were of great importance for society.
And at the same time people became convinced that the only way to discover things in
Physics [Natuurkunde] was to perform Experiments.” 125
In other words, real progress had only become possible once Artistotle’s system of knowledge
was overturned and scholars came to rely on experimental research. There is no doubt either
as to whom van Marum identified as the heroes in this story: in other lectures he speaks of
“The great Newton”, and “the sagacious Italian Philosopher Galileo”.126
Van Marum also left no doubt as to the limitations of this experimental approach, which
brings us to the second point, his opposition to extensive theorising. In an early lecture on the
compressibility of gases and liquids - in which he had alluded to “the great Newton” as well -
he concluded in the following manner:
124 For a historiographical approach to this term see: Marcus Hellyer, ed., The Scientific Revolution- The
Essential Readings (Malden: Blackwell, 2003).
“[m]et het grootste regt [...] de oude Grieken voor de waare grondleggers van verscheidene wetenschappen
gehouden worden [mogen]”; “dezelve door opzettelijke Proefneemingen te toetsen, was de smaak van die tijd
met”; “[t]ot dat men eindelijk in de voorgaande Eeuw begonnen is de Natuur door Proeven raadteplegen.”; “Wei
haast zag men, dat de zolang geleerde, en zo zeer opgebierde [unreadable] Stellingen der Scholastike Wij’sgeren
loutere verdichtselen waren; en men deed ontdekkingen, die zeer veel lichts omtrent verscheidene verschijnselen
geven, en voor de zamenleving van veel belang waren. En men wierd te gelijk overtuigd, dat de enighe
[unreadable word, manier?] om in de Natuurkunde te leren kunnen [precise sequence o f words unclear] was
Proefneemingen in het we rkte stellen.” “ 12 Lectiones publicae, varii argumenti, 1777, 78, 79, 80”, 21.07.1777,
Haarlem, NHA, Archief van Marum, vol. 529, nr. 13.
$j “De groote Newton , [d]e scherpzinnige Italiaansche Wijsgeer Galilaeus”. For statements on Newton see:
“20 Lectiones: de proprietatibus corporum, de legibus motus, et de machinis simplicibus, 1778, 79”, 25.11.1778,
Haarlem, NHA, Archief van Marum, vol. 529, nr. 13; Ibid., 09.12.1778; “20 Lectiones Hydrostaticae,’
Hydraulicae, Aerostaticae ut et de proprietatibus Aeris, Aquae & Vaporis aquei, 1779, 1780”, 17.11.1779,
Haarlem, NHA, Archief van Marum, vol. 529, nr. 13. For statements on Galileo see: Ibid., 12.01.1780. Other
statements o f van Marum’s from which he emerges as a clear proponent o f the idea o f a “Scientific Revolution”
abound. In 1779 for instance he gave an account o f the importance o f the air pump in his “eighth lesson”- Ibid
29.10.1779. '
“You see how far the compressibility of the invisible elastic fluids, of airs (I mean), extends.
To want to explain this and to want to derive this, like others, from certain shapes of their
particles seems reckless to me, as these particles themselves are entirely outside the reach of
our senses. We have to confess our ignorance again here - It seems that Man is not allowed to
know the causes of the general properties of bodies - Let us therefore be satisfied with the
knowledge of the properties themselves.”1
So, at this point at least, he was not at all enamoured with atomistic models, for the simple
matter that granular particles could not be perceived. He voiced similar sentiments many
years later, in 1799, in a different context, when he spoke of competing theories to explain the
formation of rocks. He concluded his lecture to the trustees by saying:
“Here we stand and we can find no ground to choose, out of so many conjectures that can be
made on this matter, one conjecture over the others. Let us therefore rather recognize the
limitations of our insights, and not occupy ourselves here, like other philosophers, with
conjectures about matters that are entirely outside the reach of our observationsB Let us now
acquiesce in the knowledge we have gained about the initial formation of the Earth’s Crust, in
so far as it is based on incontrovertible observations and experiences. Here our knowledge is
already very extensive”.1
It is important, however, not to equate van Marum’s rejection of far-reaching speculation with
indifference, or with a superficial approach to nature. Perhaps, if one only took van Marum’s
strong adherence to natural theology and his clear warning of the restrictions of experimental
science into account, one could suspect something akin to superficiality in his philosophy, in
the sense that his research might have constituted little more than a detailed description of
nature with the aim of underscoring its beautiful complexity. However, doing so would
constitute the grave error of overlooking van Marum’s utilitarian streak.
“Gij ziet, hoe verre de zamenpersbaarheid der onzichtbare veerkrachtige vloeistoffen, der luchten (meen ik)
zieh uitstrekke. Dezelve te willen verklären, en met anderen van zekere gedaantens hunner deeltjes te willen
afleiden is, dunkt mij vermetel [unreadable: vermekel?], vermits die deeltjes zelve geheel buiten het bereik van
onze zinnen zijn. Wij moeten dan hier weer onze onkunde bekennen - Het schijnt den mensch niet geoorloofd de
oorzaaken van de algemeene eigenschappen der lichaamen intezien - Laaten wij ons dan met de kennis der
eigenschappen zelven vergenoegen.” “20 Lectiones: de proprietatibus corporum, de legibus motus, et de
machinis simplicibus, 1778, 79”, 25.11.1778, Haarlem, NHA, Archief van Marum, vol. 529, nr. 13.
28 “Hier staan wij en weeten geenen grond te vinden om van zo veele gissingen die hier omtrent kunnen
gemaakt worden, de eene gissing boven de andere te verkiezen. Laat ons dan hier liever de beperktheid van onze
inzichten erkennen, en ons hier niet nevens andere [unreadable] wijsgeren met gissingen ophouden over zaaken
die geheel buiten het bereik onzer waameemingen geleegen zijn - Laaten wij ons nu te vreede houden met de
thans verkregene kunde omtrent de eerste vorming van de Korst der Aarde, zo verre zij op onbetwistbaare
waameemingen en ondervindingen gegrond is. Wij vinden hierbij onze inzichten reeds zeer verre uitgebreid” ;
“Geologische Leszen bij Teylers Stichting 1798-1803”, 29.11.1799, Haarlem, NHA, Archief van Marum, vol.
529, nr. 6.