I would not allow myself in my physics to touch upon metaphysical questions, and particularly this one: that mathematical truths, which you call eternal, have been established by God and depend entirely on him, as does the rest of all creation. This, effectively, is like speaking about God as a Jupiter or Saturn and to subject them to the Styx and to the Destinies rather than say that these truths are independent of him. Do not worry at all, I beg of you, about assuring and publishing everywhere that it is God who has established these laws of nature, in the same way that a king establishes the laws of his realm. Now there is nothing at all that we are unable to comprehend, if our spirit inclines us to consider it, and all of these truths are innate in our spirit, in the same way that a king imprints his laws in the hearts of his subjects, if he has the power to do so.
Descartes seems to have been desperate to convince Mersenne the friar that there is no religious reason to avoid considering any theory about the laws of nature, since these laws have been given to the world by God and, further, have been imprinted in our consciousness. Still, he chose to retract the book he had written about this subject, rather than expose himself to the dangers that lurk from less open-minded clerics, theologians, and philosophers.
Descartes had been working toward a very ambitious goal—a universal science (in Latin: mathesis universalis). And he had achieved a landmark discovery. He was able to use geometry, an abstract discipline of pure mathematics, within his theory of the universe. Descartes was able to apply geometrical principles in physics, including optics and mechanics, and in his philosophy. But with what he perceived as terrifying events taking place in distant Rome just when he was ready to publish his discoveries, Descartes turned back. He withdrew the publication of Le Monde; he hid his papers on the subject; and then he encoded the information in new papers, destroying the originals. Descartes made the numbers embedded in his text ambiguous; he achieved this by writing his numbers in a way that made them indistinguishable from symbols, so that only he could understand what he had written. The thickness of the symbols he used was Descartes' key to deciphering whether a symbol was a number or an abstract sign.
Modern scholars who have analyzed the text of Le Monde have discerned in it what they called the “Fable of the World.” Descartes was so concerned with hiding his true beliefs about nature that he even went as far as to disguise the world he was writing about. The world described in Descartes' withdrawn Le Monde is not our world. It is a mythical world that exists only in Descartes' own mind. It is his world. And in this fable of the world, the planets including Earth do revolve around the sun. Descartes could thus say anything he wanted about physics, biology, and the nature of light—one of the important topics of his book—without fear of ever being criticized. Hiding his physics by way of a “fable” was one more layer of protection Descartes built around himself. In the letter to Mersenne of November 25, 1630, Descartes wrote: “I like it very much, my fable of the world.” So why did he have to take the extreme step of withdrawing this book from publication after he heard about the trial of Galileo in Rome?
The correspondence between Descartes and Mersenne reveals much about the development of science, about the relationship between these two men, about Descartes' state of mind, about the fate of Le Monde, and it perhaps even gives us a hint about the reasons for his move to Holland.
On February 1, 1634, Descartes wrote to Mersenne from Deventer:
Mon Reverend Fere,
While I don't have anything in particular to share with you, it has been more than two months that I have not received news from you, and I thought it best not to wait any longer before writing to you; as I've more than enough proof of the goodwill that you have so kindly chosen to bestow on me, I've had no occasion to ever doubt it, but still I feared that perhaps that feeling has cooled off, since I had not made good on my promise to send you something of my philosophy. But the knowledge I have of your virtues makes me hope that you will still have a good opinion of me, once you see that I have voluntarily and entirely canceled the treatise [that is, Le Monde], thus losing four years of my work, for the purpose of giving full obeisance to the church, since it defends the opinion about the movement of the earth. And anyway, since I have seen neither thepope nor the council ratifying such a defense, done only by the congregation of cardinals established for the censorship of books, I know well that now in France their authority is such that they can make of it an article of faith. I allow myself to say that the Jesuits have aided in the condemnation of Galileo, and all the books of P. Scheiner provide enough proof that they are not his friends. But otherwise the observations in that book furnish enough evidence for the movements he attributes to the sun, that I am of the belief that P. Scheiner himself is not of the opinion of Copernicus. I find this so astonishing that I do not dare publish my own sentiment. For me, I search for nothing but rest and the tranquillity of spirit, goals that cannot be achieved by those given to animosity. I wish only to instruct others, especially those who have already acquired some credit for fake opinions and have some fear of loss lest the truth be revealed.
I am your very obedient and very affectionate servant, Descartes
Descartes never even sent a copy of the withdrawn Le Monde to his friend Mersenne. Pere Christoph Scheiner, to whose works Descartes refers, was a Jesuit astronomer who had published a treatise on sunspots. He was a good scientist and his analysis of sunspots was based on the earliest observations of this phenomenon. Galileo, however, ridiculed Scheiner's work, thus turning him into a bitter foe who then joined in the attacks against him.
Descartes appears to be jittery and fearful of the formidable forces he imagines to be arrayed against him and science in general. He seems to have a genuine, warm friendship with the friar, which he is eager to maintain. And yet, a careful reading of the letter leaves the reader with the feeling that Descartes is aware of the fact that his friend is also a member of the church. Descartes stops just short of an outright condemnation of the church, although his feelings are quite evident.
Descartes' following letter continues in the same vein, but his tone becomes harsher, and he is more blunt about the predicament in which he finds himself because of his views. We learn that Descartes' retracted treatise was probably a very interesting and valuable scientific piece of work providing support for the ideas of Galileo. The letter is datelined Deventer, end of February 1634-
Mon Reverend Fere,
I learn from your letter that the previous ones I had sent you have been lost, although I believe I have addressed them correctly. These letters explained at length the reasons why I have refrained from sending you my treatise, which I have no doubt you would have found legitimate, and far from blaming me or even going so far as not wanting to see me again, you would have been the first to exhort me, had I not been already myself resolute in my views. No doubt you know that Galileo had been convicted not long ago by the Inquisition, and that his opinion on the movement of the earth had been condemned as heresy. Now I will tell you that all the things I explain in my treatise, among which is also that opinion about the movement of the earth, all depend on one another, and all are based on certain evident truths. Nevertheless, I will not for the world stand up against the authority of the church. … I have the desire to live in peace and to continue on the road on which I have started.
In the meantime, Descartes obtained a copy of Galileo's book and was able to read for himself the heresy that had put the great scientist in peril. Descartes' next letter to Mersenne is from Amsterdam, on August 14, 1634. He writes:
I begin to feel sorrow for not having any news from you…. Mr. Beeckman came here on Saturday evening and brought me the book of Galileo, but took it with him to Dort this morning, so I had the book in my hands for only thirty hours. I haven't had theopportunity to read it all, but I can see that he philosophizes well about the movement of the earth, even though it is not enough to persuade…. For what he says about a cannon fired parallel to the horizon, I believe
that you will find quite a measurable difference, if you should perform this experiment. As for the other things, the messenger did not allow me enough time to read the material to be able to respond about these issues, and it is impossible for me to give a resounding answer on any issue of physics after my having explained all of these principles in my own treatise, which I have resolved to suppress.
Descartes clearly believed that his own writings, published or withdrawn, contained the correct answers to the problems of physics. Perhaps this is what made him feel so close to Galileo, and thus to dread a similar or worse fate. In a letter from Leyden on June 11, 1640, he writes: “You write me about Galileo as if he were still alive, and I think that he's been dead for a long time now.” Actually Galileo was alive at that time and lived for another two years, passing away on January 8, 1642. Descartes was apparently so distraught and fearful of a fate similar to Galileo's that even though he was ignorant of Galileo's fate, he assumed that the old Italian scientist must already have died—perhaps at the hands of the Inquisition. We see in these letters a portrait of an intellectual in the process of going into hiding.
Chapter 13
A Secret Affair
WHILE PREPARING HIS MASTERPIECE, the Discourse on the Method, having finally put the Le Monde debacle behind him, Descartes settled down to a reasonably quiet and happy life in Amsterdam. He lived in a building at (today's) 6 Westermarkt Street, near the West Church.
Descartes rented rooms in the building for himself and his valet from a man named Thomas Sergeant. His landlord had a pretty servant named Helene Jans, who did Descartes' housekeeping. Helene may have been a servant, but she was literate, since we know that in later years she wrote letters to Descartes. She had some education and a degree of culture. One autumn evening in 1634, while relaxing in a common area in the building at 6 Westermarkt Street, the two of them became lovers. According to Baillet, their daughter was conceived on Sunday, October 15, 1634 Clerselier reported in Paris that Descartes had told Chanut in 1644 that “it has been ten years now that God has removed me from that dangerous engagement.” And we know that the baby girl, whom Descartes named Francine, meaning “Little France,” was born on July 19, 1635. She was baptized in Deventer on August 8 in a Protestant ceremony, following the religion of her mother. Baillet has this to say about this episode:
The marriage of Monsieur Descartes is, for us, the most secret of the mysteries of the hidden life that he led outside of his country, far from his relatives and allies. This episode of his life may not have been one expected of a philosopher. But it was difficult for a man who for almost his entire life had been most interested in the workings of anatomy to practice rigorously the virtues of celibacy in order to conform with the laws that our saintly religion prescribes for those who live in bachelorhood.
After the publication of the Discourse, Descartes traveled to the Dutch coast, staying in the area around Haarlem, an isolated region of windswept sand dunes and grass. Having settled in this area, he sent for Helene and Francine to join him. Descartes wrote to a friend telling him about his move and about his desire to bring his “niece” to visit him. This was how Descartes referred to Francine, since he was hiding the fact that he had a daughter. His letter also indicated that he wanted to bring Helene to the house he was renting, perhaps to work as a maid for his landlady.
Descartes had intended to send Francine to France so that she could get a good education from a relative of the Descartes family, Mme. du Tronchet. But tragically, the girl died of scarlet fever on September 7, 1640, after three days of illness. Descartes was devastated by the death of his daughter. Years later, Descartes was attacked by a Dutch theologian named Gisbert Voetius for “having children outside the confines of marriage.” But was Francine born outside of a marriage?
There are some clues that Descartes and Helene had secretly married. The record of the birth of Francine in the registry of births in Holland lists her in a way that can very well be interpreted as referring to the daughter of a married couple. Descartes was very attached to both Helene and their daughter, Francine, and may well have secretly married the mother. Since she was a servant, Descartes wanted their relationship—marriage or other—to be kept secret. But the girl was the love of his life. Still, he wandered and did not live with them for long. After the death of Francine, Descartes viewed his relationship with Helene as a folly of youth, explaining apologetically that he was a man, that he was young at that time, and that he had never made a vow of chastity.
Three weeks after Francine died, Descartes left her mother in Amersfoort and moved to Leyden. He was brokenhearted by the loss, but kept his connection with Helene for a period of time, writing letters to her from wherever he was at the time. Eventually, the relationship ceased to exist.
Now Descartes would set his sights on women he considered more in line with his aristocratic upbringing. He became interested in a woman who was nothing less than a princess.
At about the time of the death of Francine, Descartes also lost his older sister. He was completely devastated by these deaths, and was inconsolable. He sought solace in study. But since he was alone, save for his servants, he could not exchange ideas with anyone. But as Descartes spent more and more time talking with his servant Jean Gillot, a Huguenot, he discovered that the man had a talent for mathematics. Descartes gave Gillot numerous problems to solve, and he performed admirably. It became clear to the master that the servant was better suited for mathematics than for his intended work. In a letter to his friend Constantijn Huygens (1596-1687), who was the secretary of the prince of Orange as well as a poet and amateur scientist, Descartes described Gillot as “my only disciple.” Gillot later went on to study with Huygens himself, and then studied with other mathematicians of the day. Eventually, Jean Gillot became the official mathematician to the king of Portugal—a startling achievement for a man who began his working life as a servant, and eloquent testimony to the effects of association with Descartes.
The recent deaths made Descartes aware of his own mortality. Also, when he turned forty-seven, Descartes discovered gray hairs on his head and in his goatee. He was healthy, but the discovery of gray hair made him more concerned about the process of aging, and about death. He adopted a dog, which he named Monsieur Grat. People in the little towns and villages in which he lived in Holland would often see a lonely man walking his dog, lost in thought.
Descartes changed his diet. He now ate mostly vegetables and fruits, avoiding meat almost completely. He was living in seclusion, in small towns close to agricultural areas and country markets that sold fresh foodstuffs. He would send a servant daily to the nearest market to buy fresh eggs, milk, fruits, and vegetables. Descartes had good sense about medicine and nutrition. But he wanted more. Descartes wanted to discover a way to live to for over a century.
To achieve this goal, Descartes began to visit butcher shops. He didn't eat meat—he wanted corpses of animals. He would dissect animal cadavers, studying their anatomy in careful detail. Over the years, Descartes dissected hundreds of animals of different kinds. One of the pictures of a dissected animal Descartes drew is shown below. It is a copy of the original drawing, now lost, that Leibniz made at Clerselier's house in Paris.
Descartes was interested in the relationship between body and soul. He dissected animals in part in order to learn anatomy and search for the secret of life in the hope of living a long time, and in part in an attempt to understand the relationship between the body and the soul. As we will see, Descartes' philosophy brought him to the belief that only people had souls.
Chapter 14
Descartes' Philosophy and the Discourse on the Method
DESCARTES IS KNOWN AS THE FAther of modern philosophy thanks in large part to the publication of his book Discourse on the Method of Reasoning Well and Seeking Truth in the Sciences, in 1637. The full title, in French, was Discours de la methode pour bien conduire sa raison, et chercher la verite dans les sciences, plus la Dioptriaue, les Meteores et la
Geometric qui sont des essais de cette methode. The Diop-trique, dealing with Descartes' discoveries in optics, the Meteores, detailing his theories about natural phenomena such as the rainbow, and the Geometrie, in which his important advances in geometry and its relation with algebra were explained, were three appendixes demonstrating the use of Descartes' general method. Descartes chose to write the book in French to afford it the widest possible readership among French speakers, thus following the example of Galileo, who wrote in his native Italian for a similar reason. Theirs were among the first intellectual works to be published in the vernacular, rather than the Latin of the church and the universities.
But the Discourse wasn't published in France. It first appeared in print on June 8, 1637, through the publisher Jean Maire in Leyden, Holland. The first printing of the book appeared anonymously.
Descartes' philosophy, which he explained in the Discourse (as well as in his later works), provided the basis for seventeenth-century rationalism: a trend toward emphasis on reason and intellect rather than emotion or imagination. Rationalism is generally contrasted with empiricism—the view that the main source of substantial knowledge is experience. Descartes' philosophy is based on accepting certain essential truths, not derived from experience, and seeking a system of philosophic thought based on these a priori truths while armed with a method of reasoning Descartes named “methodical doubt.” Descartes viewed the mind, God, and matter as innate ideas that could not be discerned from our sensory experience in the world.
Descartes's Secret Notebook Page 13