When The World had become ready for publication in 1633, uponhearing of the Church's condemnation of Galileo (1564–1642) in thesame year, Descartes decided against its publication. For, the worldsystem he had adopted in the book assumed, as did Galileo's, theheliocentric Copernican model. In a letter to Mersenne, dated November1633, Descartes expresses his fear that were he to publish TheWorld, the same fate that befell Galileo would befall him. And,although this is something that he understandably would want to avoid,some scholars question Descartes' expressed concern, for his livingin the Netherlands would have kept him out of reach of Catholicauthorities. The World appears to have been constituted ofseveral smaller, but related, works: a treatise on physics, a treatiseon mechanics (machines), a treatise on animals, and a treatise onman. Although much of The World has been lost, some of itseems to have survived in the form of essays attached tothe Discourse which, as was mentioned earlier, would bepublished four years later, in 1637. And, some of it was publishedposthumously. Arguably, Constantijn Huygens (1596–1687) received whatDescartes refers to as “three sheets” ofThe World, along with a letter dated 5 October 1637. These“sheets” deal primarily with mechanics.
In 1628 Descartes left Paris. At this time he seems to have beenworking on the Regulae ad Directionem Ingenii (Rules forthe Direction of the Mind), a work that he would abandon, somespeculating around the time of the move from Paris. It is worth noting that relatively recently a copy of the Rules was discovered in a library at Cambridge University. Scholars are unsure how it got there. Currently, based on what it includes, it is thought that this manuscript represents the work as it stood when Descartes had abandoned it in 1628. The later Amsterdam printing (1701) and a copy that Leibniz acquired from Clerselier (c. 1670) make certain advancements over what is found in the Cambridge manuscript. So, it appears that Descartes picked up the work again, some speculating after a visit in 1635 from John Dury (1596–1680) and Samuel Hartlib (1600–1662). The meeting took place in The Hague. Dury and Hartlib were friends of the Cambridge philosopher Henry More (1614–1687), with whom Descartes had corresponded, and of others in More's circle, including John Milton (1608–1674). Perhaps the copy was made during the visit and brought back to Cambridge. (In any event, this is a new and interesting development in Descartes scholarship.) In 1630 Descartes moved toAmsterdam. There he worked on drafts of the Dioptrique (theOptics) and the Meteors (the Meteorology),which were very likely intended to be a part of a larger work, LeMonde (The World). In 1632 he moved again, this time toDeventer, to apparently teach Henry Reneri (1593–1639) his physics. Itis also during his stay in Deventer that Descartes probably worked on afinal draft of the Traite de l'homme (Treatise onMan), which in connection to the Optics and theMeteorology was probably originally intended to be a part ofThe World.
In 1639 Descartes began writing the Meditations. And, in 1640he returned to Leiden to help work out its publication. During theyear, Descartes' daughter, Francine, died. There is evidence suggesting that he was called away fromLeiden around the time of her death, returning soon after. Some havespeculated that he left Leiden to be at her side. Also during thisyear, Descartes' father and sister died. Descartes' relationshipwith his father (and brother) was of the sort that Pierre, hisbrother, failed to even bother him with the news of their father'sdeath. Rather, it seems to have been in a letter from Mersenne thatDescartes first learns of it. In a follow up letter to Mersenne, dated3 December 1640, Descartes expresses regret in not having been able tosee his father before his death. But, he refuses to leave Leiden toattend his father's funeral, and instead stays to complete thepublishing of the Meditations.
The significance of the sort of connection that Descartes madebetween geometry and algebra was great indeed, for without it themathematization of the physics and the development of the calculusmight not have happened when they did—a generation later via Sir IsaacNewton (1642–1727) and Gottfried Leibniz (1646–1716). It should be noted, however, that as groundbreakingas this work may have been, contrary to the claims of many, nowhere in theGeometry is a “Cartesian Coordinate System” ever developed(that is, the x-y coordinate system taught to today'sstudents of algebra), nor is he the originator of other mathematicalconcepts that bear his name, for example, the “Cartesian Product”. CarlBoyer notes that various concepts that lead to analytic geometry arefound for the first time in the Geometry, and that theGeometry's mathematical notation is still used today. But, heargues, although Cartesian geometry is taken by many to be synonymouswith analytic geometry, the fact is that the fundamental aim ofDescartes' system is quite different from that of contemporaryanalytic geometry (Boyer, pp. 370–1). And so, the claim that Descartesis the originator of analytic geometry, at least as we understand ittoday, overstates the case. As Boyer rightly points out, however, thisdoes not diminish the importance of the work in the history ofmathematics.
Boeker The Mind and the World Due: October 18, 2013 Descartes presents three skeptical arguments in his meditations which shows he has reason to doubt all of his sensory beliefs.
Descartes has been heralded as the first modern philosopher. He isfamous for having made an important connection between geometry andalgebra, which allowed for the solving of geometrical problems by wayof algebraic equations. He is also famous for having promoted a newconception of matter, which allowed for the accounting of physicalphenomena by way of mechanical explanations. However, he is most famousfor having written a relatively short work, Meditationes de PrimaPhilosophia (Meditations On First Philosophy), publishedin 1641, in which he provides a philosophical groundwork for thepossibility of the sciences.
Descartes was born in La Haye on March 31, 1596 of Joachim Descartesand Jeanne Brochard. He was one of a number of surviving children (twosiblings and two half-siblings). His father was a lawyer andmagistrate, which apparently left little time for family. Descartes'mother died in May of the year following his birth, and he, his fullbrother and sister, Pierre and Jeanne, were left to be raised by theirgrandmother in La Haye. At around ten years of age, in 1606, he wassent to the Jesuit college of La Flèche. He studied there until 1614,and in 1615 entered the University of Poitiers, where a year later hereceived his Baccalaureate and License in Canon & Civil Law. Forthe history and the text of his thesis, see the following supplementarydocument:
This six part essay, translated from French to English many times in its time since the 17th century, serves to preface many of the more scientific based works of Descartes (Kraus & Hunt, 2007).
While stationed at Breda, Descartes met IsaacBeeckman (1588–1637). Notes that Descartes kept related to hiscorrespondence reveal that he and Beeckman had become more than simpleacquaintances—their relationship was more one of teacher and student(Descartes being the latter). This relationship would rekindle inDescartes an intense interest in the sciences. In addition todiscussions about a wide variety of topics in natural science, a directresult of certain questions posed by Beeckman compelled Descartes towrite the Compendium Musicae. Among other things, theCompendium attempted to work out a theory of harmony rootedin the concepts of proportion or ratio, which (along the lines of theancients) attempted to express the notion of harmony in mathematicalterms. It would not be published during Descartes' lifetime. As forBeeckman, Descartes would later downplay his influence.
After Descartes left the army, in 1619, his whereabouts for the nextfew years are unknown. Based on what he says in the Discours de laMethode (Discourse on the Method), published in 1637,there is speculation that he spent time near Ulm (Descartes apparentlyattended the coronation of Ferdinand II in Frankfurt in 1619). There issome evidence suggesting that he was in France in 1622, for itwas at this time that property he had inherited was sold—the proceedsof which would provide him a simple income for many years. There issome speculation that between 1623 and 1625 he visited Italy. Descartesemerges in 1625 in Paris, his notes revealing that he was in contactwith Father Marin Mersenne (1588–1648), a member of the Order ofMinims. This relationship would prompt Descartes to make public histhoughts on natural philosophy (science). It is by way of Mersenne thatDescartes' work would find its way into the hands of some of the bestminds living in Paris--for instance, Antoine Arnauld (1612–1694), PierreGassendi (1592–1655), and Thomas Hobbes (1588–1679).
It should be stressed that the three attached essays are importantindependent of the Discourse, for they contain much worthstudying. In the Optics, for example, Descartes works out hislaws of refraction, and within this context, what would later be calledSnell's Law (which Descartes seems to have worked out as early as1632). Further, although the Geometry would seem to have come out ofnowhere, there is evidence in Descartes's notes to himself, from whichClerselier reconstructed some of Descartes's correspondence, that hehad been working on some version of it as early as 1619. In a letter toBeeckman, dated 26 March 1619, for example, Descartes discusses thesubject matter that is found in the Geometry, and in a letterdated 23 April 1619, he explicitly mentions the book's title. It is inthis work that Descartes shows how certain geometrical problems can besolved by way of algebraic equations.