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De Zeventiende Eeuw. Jaargang 12 (1996)

De Zeventiende Eeuw. Jaargang 12

(1996)– [tijdschrift] Zeventiende Eeuw, De–rechtenstatus Auteursrechtelijk beschermd

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illustratie
Christiaan Huygens, schilderij uit 1671 door Caspar Netscher (Haags Historisch Museum, 's-Gravenhage).


The melancholic genius
C.D. Andriesse

Christiaan Huygens died three hundred years ago. Announcing his death, Gottfried Leibniz referred to his teacher and friend as ‘the Incomparable Huygens’.1. We would like to use the same phrase today, but if Huygens is to be assured of an important place in history we feel it is our duty to compare his achievements with those of other scientists. It is possible that a contemporary grieving the loss of a close friend might see that friend's achievements in a more favourable light than posterity.

It is not difficult to compare him with Galileo Galilei. Huygens was strongly influenced by Galileo and took over many of his ideas. In his youth he had assimilated the ideas of Galileo's Discorsi and later in his life he developed many of Galileo's traits and characteristics. In fact, the resemblances were so numerous that when Huygens described Galileo he was almost painting a self-portrait. Shortly before he died Huygens wrote an essay about Cartesianism, in which he distanced himself from that philosophy. In this essay we read the following:2.

‘Galileo had the acuteness of mind and knew all the mathematics necessary to proceed in science. One has to admit that he made beautiful discoveries about the nature of motion, although he left many aspects untouched. He was not so reckless and arrogant to explain all natural causes, nor was he so vain that he wished to be the leader of a sect. He was modest and truthful. Yet he thought he had acquired eternal fame with his discoveries.’ It was as if Huygens were looking at himself in one of his own carefully polished and silver-plated mirrors.

This comparison with Galileo, although appropriate, is insufficient as an evaluation of Huygens' work and character. The scientific revolution of the 17th century involved many scientists and posterity therefore is able to compare Huygens with many other actors. How, for instance, does he compare with the man who received practically all the honours? The answer to this tricky question is to be found in the background story of Huygens' greatest work.

 

The most important step on the way to this work, Horologium oscillatorium, was the proof that the weight of an isochronous pendulum follows a cycloid and that this path is the evolute of another cycloid. Above the proof Huygens wrote: ‘Magna nec ingenijs investigata priorum’ (This is something great which has not been investigated by geniuses of the past).3. In other words, he knew he was a genius - there is no doubt about that. He completed the proof on 15 December, 1659, and took its motto from Ovid's Metamorphoses, which he had read when he was only 12. Now, having reached the age of 30, he felt he had made his greatest discovery. Only one week earlier he had told Frans van Schooten in a letter: this is ‘certainly the finest thing I have ever come across’.4.

He had indeed made a great discovery. He had found that the period of a pen-

dulum will be independent of the swing, if the pendulum is deflected by platelets shaped like cycloids. But more important than this finding itself was the way in which he had arrived at his conclusion. In fact he had used the method of infinitesimal analysis. Later on, however, he was reluctant to accept formal calculus, for although he understood its roots very well he found the rules obscure. Huygens was a master at summing indefinitely small line elements and an expert at using infinitesimal triangles.

It was quite some time before Huygens' greatest work, Horologium oscillatorium, was published. This book about the pendulum clock was his tribute to the Academy of Science in Paris, or rather to the French king. By that time, 1673, Huygens had become the recognised leader of European science. Isaac Newton, who received a copy of the book via the secretary of the Royal Society in London, reacted immediately. In a letter to the secretary Newton commented that the book was very worthy of its author but that he had an easier proof of the isochronous property of the cycloid.5. ‘If he (Huygens) please, I will send it him.’

In this simpler proof Newton used the calculus which he had invented eight years before but had kept secret. Now he was willing to share his secret with the author of Horologium oscillatorium! What greater honour could Huygens receive? But Huygens declined the offer. He did not ask for the proof, probably because he was still offended. Only three months earlier Newton had wrecked their correspondence about light and colour by addressing Huygens like a delinquent schoolboy.6. Thereupon Huygens had put an end to the exchange of letters with the following polite but icy words:7. ‘In view of the fact that he (Newton) upholds his doctrine with some fervour, I am not interested in continuing this dispute.’

This is drama. Collaboration between these men might have produced great things. Although they clearly did not like each other, each recognised the other's qualities. For instance, in Newton's letter about Horologium oscillatorium which ended with theses on centrifugal force, he urged Huygens to publish more about this force since it ‘may prove of good use in naturall Philosophy & Astronomy as well as mechanicks’.5.

Since Newton himself had discovered the properties of centrifugal force in 1665 (five years after Huygens) he knew what he was talking about. Horologium oscillatorium had made public what Newton thought was known only to himself. From that time onwards, therefore, any scientist could infer (and Newton had inferred it in the mean time) that the force that kept planets in orbit round the sun must become weaker with the square of the distance to the sun. In addition, any scientist could now generalise the proportionality between force and acceleration (the essence of Huygens' theses) to what is known today as Newton's second law. Huygens had indeed hit on something that could be put to good use in both astronomy and mechanics.

 

Huygens was urged by Newton to publish more but chose not to do so, even though he had in fact written a complete treatise on centrifugal force. The treatise, De vi centrifuga, is dated 15 November, 1659. This was precisely one month before he completed his proof of the isochrony of the cycloid. He was reluctant to publish his treatise on centrifugal force because he was not satisfied with it. However, after his death Burchard de Volder and Bernard Fullenius decided to publish the treatise

because they believed they were acting in accordance with Huygens' last will and testament. By that time, however, Newton's Principia mathematica had made its impact. We can say, therefore, that Huygens' treatise was published twenty years too late. In a sense publication also came two hundred years too early. By then, Albert Einstein, not without acknowledging his debt to Huygens, was deducing the ultimate consequences of the relativity of motion.

Why did Huygens not wish to publish De vi centrifuga? The most likely reason is that it did not clarify what was relative in circular motion. This was a weak spot in the otherwise brilliant treatment of moving frames of reference, even when accelerated. When the time came for Horologium oscillatorium to be printed he was confused about the relativity of circular motion and thought that it might in fact be absolute. Later on, three or four years before his death, he returned to the problem. Now he rejected the notion that circular motion could be absolute, thereby also rejecting Newton's idea of absolute space, and attempted to solve the problem in words:8.

‘Rotation is a relative motion of parts driven in different directions but kept together by a string or connection. But can one say that two bodies move relative to one another if their separation remains the same? This is perfectly possible provided an increase in the separation is prevented. In fact, on the circumference (of a wheel) there is opposite relative motion.’

Huygens believed in the complete relativity of motion, as firmly as he believed in the law of inertia, but he did not fully understand that these two concepts were in conflict with each other. ‘Their inconsistency’, wrote Einstein,9. ‘was illuminated very clearly by Mach, but it had already been recognized with less clarity by Huygens and Leibniz.’ This praise by Einstein may be excessive, but Huygens was no doubt the first person to take relativity seriously. He wanted to study all its consequences, even if this meant withholding his treatise on centrifugal force, which could have been his greatest contribution to science. He chose a very fitting motto for De vi centrifuga. He took it from Horace's letters, which he had also read when he was only 12 years old: ‘Libera per vacuum posui vestigia princeps’ (I was the first to take free steps through emptiness).10.

 

By lingering so long at the summit of Huygens' achievements we are inclined to forget about the rest of the mountain below. There is much to be said about his other work too. One thing we must certainly do is dispel the myth that the remainder of his work is a heap of boulders, a heap of casual findings. Another thing we must do is discard the notion that it must be a monolith, representing one grand idea. Isn't it time we stopped regarding history as a dialectic of grand ideas? For grand ideas are always poorly defined, loose constructs which, on close examination, burst like soap bubbles. Huygens, for instance, began by accepting the breathtaking conjectures of René Descartes, but later in life he produced subtle arguments to shatter these conjectures. When Huygens worked with the ideas of others, he elaborated and renewed these ideas and added important elements. To him ideas were flexible tools with which he tried to get a grip on the world. His findings were certainly not casual.

Let us take a look at his early work on collisions which are contained in the unpublished treatise De motu corporum ex percussione, dated 1656. In this work he used

not only Galileo's idea of relativity but also an idea of Evangelista Torricelli, namely that the centre of gravity of many bodies lies as low as is physically possible. ‘Nisi principium ponatur nihil demonstrari potest’ concluded Huygens (Nothing can be proved unless this principle is laid down).11.

Recognising the significance of this principle, he rephrased it several times. He first used the principle in 1646 when he tried to prove that the catenary is not a parabola.11. He rephrased it in 1650 for his extensive study of floating bodies12. and arrived at the brilliant generalisation of 1652, when he wrote his equations for the conservation of kinetic energy, the name given to them today.13. The philosopher may not realise that these algebraic equations are in fact a rephrasing of the principle, but the physicist is stunned by the boldness.

Why Van Schooten discouraged Huygens from publishing his treatise on collisions is a story on its own.14. Suffice it to say that publication would have dealt Cartesianism a blow. But the treatise played an important role in the development of Huygens' thinking. Let us take a look at his later work on light, namely his Traité de la lumière of 1677, published in 1690. Because he regarded light as a wave-effect in ether he had to return to collision theory. The Cartesian idea was that ether was a space filled randomly by myriads of invisibly small particles. Therefore the rectilinear propagation of light, as well as its reflection and refraction, could only be explained in terms of a summation of pulses caused by all kinds of collisions between these particles. Despite his mastery of mathematics Huygens could not find satisfactory solutions based on collision theory.15. Realising what mathematics was needed to explain the propagation of light he silently abandoned the idea of colliding particles and invented a new principle. This principle was yet another blow to Cartesianism. The principle proved to be correct and accurately described electromagnetic waves, waves which had still to be discovered.

 

To complete this survey of the mountain, we return to the persistent view that history is a dialectic of conflicting grand ideas. Once upon a time Georg Hegel tried to prove that ideas were identical to realities. He used the curious argument that reality is ‘mind-like’ and therefore reasonable, just as any idea must be. Physicists find such a theory difficult to accept. To physicists (and to most thinking people) the ideas in our mind are different from realities or facts of nature. Ideas can conflict with each other, but facts can't. Hegelianism, however, is still around today - in paradigms, methodologies and research programmes. Its continuing influence has not helped Huygens' reputation and has lowered his status in the history of science.

Alexandre Koyré was the first to misjudge Huygens' work by putting it under Hegel's microscope. ‘Huygens’, according to Koyré,16. ‘paid a tremendous price for his fidelity to Cartesian rationalism à outrance.’ Richard Westfall17. used the same microscope and concluded that, if Huygens were to have pursued his ideas on dynamics, ‘it is reasonable to speculate that textbooks today would refer to Huygens' two laws of motion instead of to Newton's three.’ Eduard Dijksterhuis,18. who may have had just as much affinity for physics as for history, took a broader view, but still saw an idea as dominating Huygens' work, namely the idea of the mechanisation of nature.

Will we ever get rid of the grand ideas? Can't we start to appreciate the subtle

pragmatism of Huygens' work? Some day soon Joella Yoder19. will be ready to help us by using this approach.

 

So far we have concentrated on Huygens, the genius. Now let us turn to Christiaan, the man. We have already seen how scrupulous and painstaking he was. This characteristic is a key to both the brilliance of his mind and anguish of his soul: ‘Tristitia quodcumque agitat mens inficit aegri / Nec tibi judiciis propriis tunc fidere fas est’ (The mind infects whatever it touches with a miserable sickness / and at such a time it is not right to trust your own judgements).20. He wrote these verses during his later years at Hofwyck. Immediately we step into another emptiness, and in a way we are the first to do this.

It has become customary to say that Christiaan's character is difficult to fathom. It is as if he were impenetrable like a statue. A century ago Johannes Bosscha, second editor of the Oeuvres complètes and secretary of Holland's association of sciences, addressed a meeting commemorating Huygens' death. He began his speech about Christiaan thus:21. ‘Paying one's last respects to a friend is one of the greater griefs of life. In our eyes he is an image of noble seriousness, undisturbed by fleeting passion, an image of clarity hardly touched by the commotion of life.’ When a man has been praised to high heaven, one wonders whether he can ever be brought back to earth.

Let us try and bring Christiaan back. We will now compare some of his letters with texts about Christiaan written by his father, Constantijn, the redoubtable poet-diplomat. Father and son had very different characters; the son appears pale compared to the father. Christiaan was reserved, tending to stand aloof from social events and ceremonies. We see this attitude in the following episode. No sooner had Christiaan finished his great work of 1659 than he had to attend the wedding of his sister Suzanna. Whereas Constantijn describes the party with all its sounds, smells and colours22. - mentioning the copious dinner, the kisses over the wine, the 1600 candles at the ball, the musicians, the near-uproar outside the bride's room - Christiaan (in a letter23.) regrets how much time he wasted on the ‘compulsory’ merriment.

We know of only one letter by Christiaan describing a kind of merriment. Christiaan wrote it when he was 26; accompanied by three young men he went on a ‘grand tour’ through France - the country where he was later to be bathed in glory. To an acquaintance in the Hague he wrote thus:24. ‘I wish you had a flying horse (...) so that you could be with us, either on our trip when we floated down the Loire or when we performed a heroic deed, for instance when we decided by the “lot del fortunato dado” who should sleep alone and who with another, or when we needed a new horse and had to choose out of four, the best of which was blind...’ The trip down the Loire was to Angers where Christiaan had to buy a doctorate-in-law by order of his father.

He wrote to his father on the matter:25. ‘When we get back with the diploma I shall do my best to perceive the world as you understand it, and I think it will be possible to do that if you are kind enough to let me have the time.’ A Byzantine sentence. Christiaan was never able to free himself from the redoubtable Constantijn. It is significant that when his father died at the age of 90, Christiaan had a portrait painted of himself in which he was depicted as an orphan26. - an orphan aged 58.

Christiaan shaped and moulded the text of his letters as if he were grinding a lens. The mastery of mathematics gave him access to the physical world, the mastery of his passions gave him access to himself. He must have thought along these lines, as did the virtuosi of the Renaissance who served as an example to Constantijn. Even when angry, Christiaan was usually able to retain his composure. Nevertheless he did write quite a number of angry letters; there is one about Eustachio Divini who attacked his ring hypothesis regarding Saturn,27. and there is another about Robert Hooke who contested Christiaan's claim to have invented the balance spring for a watch.28. His rage was boundless in a letter about Father Catelan, who maintained that there was an error in Horologium oscillatorium. He wrote as follows:29.

‘I am amazed at his attack on my theory about the centre of oscillation; nobody has objected to it in the 9 years since I published it. Having looked at his so-called refutation, I wonder why the author has not withdrawn it during the 7 months since its publication. Briefly, what Catelan thinks is that the sum of two line elements cannot be equal to the sum of two other line elements if the ratio of these elements is different. Imagine that the first two measure 4 and 8 feet and the other two 3 and 9 feet, and see whether you can make either sum come to anything else but 12. (...) I want this to be published so that those who are not familiar with my proof will realise that Catelan's remarks are meaningless. Should he take up the issue again, I would be obliged if you submit his views to a scholar before you publish them. This might even be good for his reputation. To tell the truth, I dislike being attacked by a blockhead.’

Even when abusing others, Christiaan retains a degree of equilibrium. So did he ever lose his temper? What did he mean when he wrote about the sickening of the mind? In his works we do indeed find traces of disintegration and darkness. Not only his diaries and notes written on loose sheets but also his polished letters reveal unpleasant sides of his character: cunning, lust for money, dirty tricks, fornication, self-pity, angry outbursts. He was extremely rude to Isaac Thuret who dared to apply for a patent on the balance spring Thuret had helped to develop.30. He played a dirty trick on Nicolaas Hartsoeker by presenting Hartsoeker's microscope as his own.31. He treated these men as inferiors, as servants. His behaviour may have had social roots.

He was not courteous to Gilles de Roberval either. Roberval was the only colleague in the Academy of Science in Paris who could be his match. He had criticised Christiaan's pulse theory of gravity in clear, strong terms. He had argued that the pulses in Christiaan's device for explaining gravity did not have to be directed towards a centre.32. It is both reprehensible and offensive to counter such a penetrating argument by the simple statement ‘that the reason I give for the particle to be pushed towards the centre is very clear, and it cannot be disputed.’33. This critique, aggravated by Roberval's objections to his way of calculating oscillation centres, prompted a crisis.

 

We will now say something about Christiaan's melancholy, a trait in his character which we notice immediately. Should we compare his ‘melancholia hypochondrica vera et mera’ with the spleen in the poetry of Charles Baudelaire? Perhaps, but there is an important difference; the various depressions that Christiaan ex-

perienced fit into a pattern. The depression of 1670, possibly the deepest, followed directly after the debate with Roberval. Francis Vernon, a secretary at the English legation in Paris, has left us a moving description of his visit to Christiaan during this illness:34.

‘His weaknesse & palenesse did sufficiently declare how great a destruction his sicknesse had wrought in his health & vigour & that though all was bad, wch I saw, yet there was something worse whch the eye could not perceive nor sense discover, which was a great dejection in his vital spirits, an incredible want of sleep, wch neither hee, not those who counceld & assisted him in his sickness knew how to remedie.’ He feared that he was ‘neare to the very Point of Death’ and complained that the Academy was ‘mixt with tinctures of Envy’, since it was completely dependent on the favour of a minister. As a result of this depression Christiaan was unable to work for almost a year and had to return to Holland to recover.

We can easily guess what prompted his depressions in 1675, 1679 (in the months around his 50th birthday) and 1681. They may have been brought on by the ineffectiveness of his patent on the balance spring, by the intrigues that followed the trick he played on Hartsoeker and by the comet debate (which was won by Ole Römer). He would stay in bed as if paralysed and let himself be carried by a servant.35. Members of the family who came to see him in Paris started talking about his guilty conscience. His older brother noted that he seemed ‘to be afraid of vicars’36. and his sister provided him with a nurse, beguine Latour, but she was unable to help him.

Interestingly, his illnesses, at least those of 1691 and 1693, occurred not only in France but also in Holland. Sometimes it is difficult to distinguish them from the colds accompanied by a splitting headache, from which he suffered all his life. The first headache is mentioned in a letter of 1652 in which the genius describes how this ‘capitis dolor’ interferes with his studies.37.

A biographer attempting to interpret this melancholy has to venture into barren land, or into emptiness.38. What is the cause of this debilitating force? It's certainly not mental exhaustion after a period of activity and creativity, as the events of his life make clear. What are the properties of this force? Christiaan does not write about his suffering. Or was he in fact doing so when he noted in the margin of a loose sheet that ‘without satisfactory business the mind yields to casual passions which often do harm to others’?39. If so, this again points to feelings of guilt. Not only this comment but many other hints give the impression that his work had become a refuge from the indefinite ‘tristitia’, a real abyss.

 

Perhaps we can attempt to understand Christiaan's melancholy by following in the footsteps of Sigmund Freud.40. ‘Melancholy’, wrote Freud, ‘is characterised by profound dejection, by the loss of interest in the outside world and the loss of one's selfrespect, which is expressed in self-reproach and sometimes in the anticipation that one will be punished. We can understand this syndrome somewhat better if we bear in mind that the symptoms of mourning are almost identical, the only difference being that (in mourning) one's self-esteem is not impaired.’

The next step in the Freudian approach is to identify what has been lost. Whereas mourning is the reaction to the loss of a loved one, melancholy, which impairs one's self-respect, may be a reaction to the loss of a dearly loved part of one's ego. Freud assumed that the ego is, or can be, split into several parts. But this lost

part of the ego cannot be buried; it is as if it remains present in the person and can never be detached. The person in mourning, however, is detached from his or her loved one.

A major symptom of melancholy is insomnia. Insomnia testifies to a person's inability to abandon all occupations, complete abandonment being necessary to fall asleep. We have ample evidence of Christiaan's insomnia. There is another major symptom of melancholy. Following the loss of part of an ego, the ego that remains will regard itself as worthless and reprehensible. The melancholic rails at himself and expects to be driven out and punished. According to Christiaan's sister-in-law who often came to see him in the last few months of his life, Christiaan presented these symptoms and displayed this kind of behaviour.41.

If there is some truth in this interpretation, let us now consider what part of his ego Christiaan may have lost. According to Freud's theory it would have been the part he valued most. In Christiaan two strands, two lives were in competition: the personal life and the intellectual life. Arthur Schopenhauer described such a dichotomy:42. ‘A privileged man (like a genius) is living a second life in addition to his personal life, namely an intellectual life, which gradually becomes his only goal, and the first life is then regarded simply as a means (to reach this goal). This intellectual life is his primary occupation, and the continuing growth of his insight and knowledge makes it more coherent, ever more intense, persistently more complete and integrated, as if a work of art is being created.’ Was it then this life that Christiaan lost? Was it his genius that he lost?

We can ask questions, but our answers can only be tentative because a man's soul defies analysis. If Christiaan's melancholy of 1670 was due to a ‘loss of genius’ as a result of being exposed to Roberval's profound intellectual critique, then he must have been preoccupied by the notion that either his ego had to be smarter than anyone else's or it had to cease to exist. This attitude probably stemmed from his constant striving to perceive the world in the same way as his father. Christiaan's melancholy, however, was not just the result of a ‘loss of genius’, it was mingled with symptoms of true mourning.

 

As we have seen, in his deepest melancholy Christiaan asked to be carried around - like a child. This may have been connected with his early memories about his mother's death. He was only 8 years old when his mother Suzanna lay on her deathbed and he was the only child to be admitted to the sickroom.43. He had to be lifted up so that he could see his mother. She kissed him goodbye, saying: ‘Kom hier mijn soete mannetie, laet ick u eens kussen.’

Six months later the boy, unlike the other children in the family, was still wearing a ‘mourning skirt’.44. Suzanna and Christiaan were said to resemble one another in that they were both of a calm and serious disposition. But several years before his mother's death Christiaan would sometimes withdraw into himself.45. However, he is also said to have been very obedient and helpful, although easily hurt. At a very early age he learned to take refuge in an inner world, the world of the intellect. As he grew older it became increasingly difficult for him to find any comfort in the world outside his intellectual world. Perhaps this can help us to understand the drama surrounding his death.

His older brother has left us a description.41. Christiaan lay in a darkened room

in a house in the Noordeinde in the Hague. He was in pain, he started to cut himself with glass splinters, he refused food because he thought it was poisoned, he shouted deliriously that ‘people would tear him to pieces if only they knew what he thought about religion’. When he finally agreed that the vicar be summoned, it was because he felt he no longer had the strength to resist his family's wishes. But even in the presence of the vicar he stuck to his views - although we do not know what these were. ‘The Reverend Olivier addressed him for a long time’, wrote the brother, ‘and prayed for him, but he is not willing to change his mind. Sadness all round.’ During the night he loses consciousness. At half past three in the morning the family is informed.

When Christiaan Huygens disappeared into the emptiness on 8 July, 1695, his shocked family is unlikely to have grasped that this scrupulous mind in a wasted body had been craving for clarity right up to the end.


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