How Descartes completes his course of Philosophy and learns Mathematics

The kingdom was then divided by the parties formed between the princes and some lords on the one hand, and those who had the administration of affairs on the other; and public peace was troubled by a civil war which was considered the third of its kind since the death of King Henry IV.

Descartes at 21 wanted to enter the service.

The annoying people of his age and quality had put him out of a state to return to his retreat, or to be able to take advantage of it. This is what made him decide to leave the city, after having had permission from his father. His duty combined with his inclination led him to want to join the king’s troops; but it was necessary to take some measures so as not to appear to be a partisan of Marshal d’Ancre, whose domination had become odious to the king’s best servants.

The pretext of this unbearable domination kept the Duke of Nevers, the Duke of Vendôme, the Duke of Mayenne, and Marshal de Bouillon away from the court, and in a kind of rebellion against the state. So it was neither glorious nor honest to serve in their armies.

He therefore thought of joining the king’s armies under the Duke of Guise or the Count of Auvergne, when the desire to see foreign countries inspired him with the plan to go and serve among peoples who were allies of the king.

In this, he proposed to himself the example of several young gentlemen of the French nobility, who were then going to learn the trade of war under Prince Maurice of Nassau in Holland.

He was preparing his gear when he learned of the death of Marshal d’Ancre who was killed at the Louvre on Monday, April 24, by the men of Mr. de Vitry, captain of the bodyguard. This accident, followed by the recall of the discontented to the court, changed the face of affairs in the state; but it did not make Mr. Descartes change his mind. He left for the Low Countries around the beginning of May, and went straight to Dutch Brabant to join the troops of Prince Maurice as a volunteer.

The United Provinces were then enjoying the peace that the truce concluded on the ninth of April of the year 1609 with the Spanish for a period of 12 years had procured for them. But the suspension of arms was hardly noticed among the Dutch troops, which Prince Maurice took care to keep in check by continuous exercises.

The army was spread out in the border towns, and particularly in the territory and the city of Breda, which was considered a property belonging to the House of Nassau, although it was incorporated into the republic of the provinces.

Prince Maurice, then 50 years old, was recognized throughout Europe as a great captain.

He was prudent, valiant, and tireless at work. He was given no equal in the art of besieging or relieving a place; of fortifying a camp; of surprising the enemy; of observing discipline among the troops. But above all, he was very good at mathematics; he loved mathematicians and engineers; he perfectly understood fortifications; and had already invented several machines to cross rivers and besiege cities.

It may be that these last qualities particularly attracted Mr. Descartes to this prince. But it must be admitted that his intention was not to become a great warrior at his school, although he had sought this opportunity to learn the trade of war under him. In deciding to bear arms, he made the resolution not to be a player anywhere, but to be everywhere a spectator of the roles played in all kinds of states on the great theater of this world. He had only become a soldier to study the different customs of men more naturally; and to try to put himself to the test of all the accidents of life. In order not to be constrained by any superior force, he first renounced all charges and always maintained himself at his own expense.

But to keep up appearances, it was necessary to receive the pay at least once: just as we see that pilgrims who are well-off and provided for themselves otherwise believe themselves obliged when leaving for their pilgrimage, to ask for alms at least once, so as not to let the custom that wants one to take the posture of a suppliant and a beggar perish. He was curious to keep this pay all his life as a testimony of his military service.

He testifies that he truly loved war at this age: but he claims that this inclination was only the effect of a feverish warmth, which having subsided in the course of time, also made this inclination fall away. As it was only a matter of temperament, and a somewhat disordered temperament, it did not turn into esteem for the profession of arms, when he had occasion to explain what he thought of it. This is what he made known to one of his friends in these terms. “Although custom,” he said, “and example make the profession of war esteemed as the noblest of all: for me, who consider it as a philosopher, I esteem it only for what it is worth, and I even have a lot of difficulty giving it a place among the honorable professions; seeing that idleness and debauchery are the two main motives that lead the majority of men to it today.”

He spoke in this way from the experience he had of others. For as for himself, he always showed himself to be a great adversary of idleness and debauchery, either in his military occupations, to which he brought all the assiduity of the most ardent soldier, or in the leisure that his functions left him, and which he used for study, when others gave it to debauchery. On the proofs he gave in some unforeseen encounters of his courage and his conduct, one will easily believe the authors who claim that his sword acquired him the reputation of a brave man, although he did not aspire to this glory at all.

But no one will ever believe Mr. Borel, who states that Mr. Descartes was at the siege of Breda twice, when it is known that he was in Holland for only two years at this time, and that the city of Breda did not suffer any siege during this interval when the truce was still in effect. Since the year 1590 when this city had been taken by Prince Maurice, it remained under the power of the states until 1625 when the Marquis of Spinola put it back under Spanish domination after a siege of almost ten months; and it was not retaken by the Dutch until the year 1637.

This city was therefore in a complete rest under the government of Prince Maurice during the two years that Mr. Descartes bore arms in Holland; and this tranquility gave occasion for the curious to come there to see the court of the prince, and the works of the mathematicians and engineers who worked under him.

It was at similar encounters that Mr. Descartes found himself indebted for the knowledge and friendship of Mr. Isaac Beeckman. This man, versed in philosophy and mathematics, was rector or principal of the college of the city of Dort, and taking advantage of the proximity of Breda, which is only five leagues away, he was quite often at the court of Prince Maurice, and came to see particularly Mr. Aleaume, his mathematician, and the other engineers.

Beeckman was actually in the city of Breda, when an unknown person had a mathematical problem posted in the streets to propose it to scholars and ask for its solution.

The problem was conceived in Flemish, so that Mr. Descartes, who, having newly arrived from France, did not yet understand the language of the country, was at first content to learn that it was a problem proposed by a mathematician who was not named, but who flattered himself with making himself known gloriously by this fact.

Seeing the concourse of passers-by who stopped in front of the poster, he asked the first one who was near him to tell him in Latin or in French the substance of what it contained. The man to whom chance made him address was willing to give him this satisfaction in Latin: but it was on the condition that he would oblige himself on his side to give him the solution to the problem which he judged to be very difficult in himself.

Descartes accepted the condition with such a resolute air, that this man, who expected nothing of the kind from a young army cadet, gave him his name in writing with the place of his residence, so that he could bring him the solution to the problem, when he had found it.

Descartes knew from his note that he was called Beeckman: and he had no sooner returned home than, having set about examining the problem on the rules of his method as with a touchstone, he found the solution with as much ease and promptness as Viète had once brought to solve in less than 3 hours the famous problem that Adrien Romain had proposed to all the mathematicians of the earth.

Descartes, so as not to fail in his word, went to Beeckman’s the very next day, brought him the solution to the problem, and even offered to give him the construction of it if he wished. Beeckman seemed very surprised: but his astonishment increased completely differently, when, having opened a long conversation to sound the mind and the capacity of the young man, he found him more skillful than him in sciences that he had been studying for several years. His conversation made him feel that he was something else entirely than what the solution to the problem of the unknown person had made him appear to be.

He asked him for his friendship, offered him his, and asked him to consent that they maintain a mutual exchange of study and letters for the rest of their lives. Mr. Descartes responded to these courtesies with all the effects of a sincere friendship: and to give him marks of the confidence he had in him, he gladly consented that he be his correspondent for Holland, as he had wished. Their relations lasted until 1636 or 1637, that is to say until Beeckman’s death.

Their friendship suffered a slight interruption a few years after Mr. Descartes had established himself in Holland as a philosopher: but it was of short duration, and Mr. Beeckman, who had caused it by a lack of conduct, took care to repair it. Mr. Descartes also practiced acquaintances with other mathematicians of the United Provinces, and above all with an Isaac of Middelburg who proposed various questions of mathematics and physics to him during his first stay in Holland.