Le Monde ou le Traité de la lumière et des autres principaux objets des Sens. Avec un discours du mouvement local et un autre des fièvres, composez selon les principes du même auteur.

Paris: Michel Bobin & Nicolas le Gras, 1664.

First edition, in a contemporary armorial binding with a noble provenance, of Descartes’ first account of his influential system of physics based upon vortices, written in the early 1630s. His great achievement was to develop a system of physics based on a simple theory of matter and a few simple laws – very similar to Newton’s laws of motion – which also allowed him to account for all the known properties of light. “Descartes’s first attempt to explain the formation of the physical world was composed during the 1630s but suppressed, like L’Homme, after Galileo’s condemnation. In it Descartes gave his account of cosmogony strictly in terms of matter in motion, making the laws of motion the ultimate ‘laws of nature’ and all scientific explanation thus ultimately mechanistic” (Norman 629). Descartes’ main aim was ‘to establish that the cause of light is motion’, a goal that required formulating ‘an explanation of qualities, a theory of matter, laws of motion, an explanation of the heavens, and a theory of perception’. As part of his matter theory, he published a definitive account of his mechanical philosophy, in which all things were composed of corpuscles of matter in a plenum, or a ‘full’ universe of finer and finer particles that swirled in vortices. “The World raised one of the central issues in seventeenth-century theory of knowledge, in its very first chapter, concerning the possible difference between the way in which things are in reality and the way in which we perceive them. This question had already been raised by Galileo in 1623. Its significance for the new sciences is difficult to exaggerate … Descartes addresses this question in the first sentence of The World. ‘Since my plan here is to discuss light, the first thing that I want to bring to your attention is that there may be a difference between our sensation of light, i.e., the idea which is formed in our imagination by means of our eyes, and whatever it is in the objects that produces that sensation in us, i.e., what is called ‘light’ in the flame or the sun’” (Clarke, p. 115). “The official reason Descartes gave for withholding his World from publication was the church’s condemnation of Galileo, and the fact that his own book assumed the same heliocentric theory that had provoked that judgment” (ibid., p. 121).

Provenance: Louis Guillaume de Bon de Saint-Hilaire (1715-1773) (arms on covers) – Marquis de Saint-Hilaire, Baron de Fourques, advisor to the Cour des Comptes, Aides et finances de Montpellier from 1734, first president of this court in 1744, first president of the sovereign council of Perpignan in 1754, intendant of Roussillon.

“Descartes’ achievement in the Treatise on Light [i.e. Le Monde] is two-fold. In the first place, his vortex theory explains the stability of planetary orbits in a way that presents an intuitively plausible picture of orbital motion which requires no mysterious forces acting at a distance: the rapid rotation of the Sun at the centre of our solar system, through its resultant centrifugal force, causes the ‘pool’ of second matter to swirl around it, holding planets in orbits as a whirlpool holds bodies in a circular motion around it. Moreover, it explains this motion in terms of fundamental quantifiable physical notions, namely centrifugal force and the rectilinear tendencies of moving matter. In other words, the heliocentric theory is derived from a very simple theory of matter, three laws of motion, and the notion of a centrifugal force. Secondly, this account also enables Descartes to account for all the known principal properties of light, thereby providing a physical basis for the geometrical optics that he had pursued so fruitfully in the 1620s” (Stephen Gaukroger (ed.), Rene Descartes: The World and Other Writings, 1998, p. xxiii).

Le Monde was part of a larger project that Descartes began in October 1629, and then abandoned, on hearing of the condemnation of Galileo, at the end of 1633. It was originally designed to cover three topics: inanimate nature, the physiology of the human (and animal) body, and the ‘rational soul’. The first two parts were published posthumously, as the present work and De Homine (1662), respectively, but the third part is lost and may never have been drafted. The project also included the material on the formation of colours in the Meteors and the material on geometrical optics in the Dioptrics, both subsequently published in 1637 along with the Discourse and the Geometry.

In the first five chapters of Le Monde, Descartes sets out his corpuscular theory of matter. He explains heat and light as being due to the agitation of these corpuscles. This agitation is also what gives substances their properties, including whether they are fluid or solid. Descartes believes that these corpuscles are packed together such that there is no void or empty space in nature. He describes substances as consisting only of three elementary elements, fire, air and earth; the properties of any substance can be characterized by its composition of these elements, the size and arrangement of the particles in the substance, and the motion of its particles.

In the next two chapters, Descartes introduces his three laws of motion, which are designed to describe the collisions of corpuscles. The first law tells us that a body conserves its motion except in collision, when, the second law tells us, the total motion of the colliding bodies is conserved but may be redistributed amongst them. It is left to the third law to tell us about direction, and according to this law, because a body’s tendency to move is instantaneous, this tendency to move can only be rectilinear, because only rectilinear motion can be determined in an instant: ‘only motion in a straight line is entirely simple and has a nature which may be grasped wholly in an instant’. Motion in a circle or some other path would require us to consider ‘at least two of its instants, or rather two of its parts, and the relation between them’. What path the body will actually take, however, will be a function of the collisions to which it is subject.

In chapters 8 to 12, using the theory of matter and laws of nature which have now been elaborated, Descartes sets out the details of a complete heliocentric cosmology, from the formation of the Sun and the stars, the planets and comets, the Earth and the Moon, to weight or gravity and the tides. The key is his account of vortices. The universe, as Descartes represents it, consists of an indefinite number of contiguous vortices, each with a sun or star at the centre, and planets revolving around this centre. Occasionally, however, planets may be moving so quickly as to be carried outside the solar system altogether: then they become comets. Planets eventually enter into stable orbits, the less massive they are the closer to the centre, and once in this orbit they are simply carried along by the celestial fluid in which they are embedded. The stability of their orbits arises because, once a planet has attained a stable orbit, if it were to move inward it would immediately meet smaller and faster corpuscles of which would push it outward, and if it were to move outward, it would immediately meet larger corpuscles which would slow it down and make it move inward again. Descartes then moves on to explain the motions of planetary satellites and the diurnal rotation of a planet like the Earth. The celestial matter in which the Earth is embedded moves faster at one side of the planet than at the other, and this gives the Earth a ‘spin’ or rotation, which in turn sets up a centrifugal effect, creating a small vortex around itself, in which the Moon is carried. Turning next to consider what the weight (pesanteur) of the Earth consists in, Descartes rejects the idea of weight as an intrinsic property. In earlier writings he had defined weight in functional terms as ‘the force of motion by which a body is impelled in the first instant of its motion’; he has no hesitation in offering a similar account here. Finally, the phenomenon of the tides is explained using the same ideas.

The jewel in the crown of Le Monde is the theory of light set out in the last three chapters: it provides an empirical, quantitative account of a physical question whose explanation derives directly from his mechanist cosmology. Descartes’ purpose is to show how the behaviour of light rays can ultimately be explained in terms of his theory of the nature of matter and the three laws of motion. Indeed, the theory of matter turns out to be motivated directly by the requirements of Descartes’ physical optics, for the first element makes up those bodies that produce light, namely suns and stars; the second element makes up the medium in which light is propagated, namely the celestial fluid; and those bodies that refract and reflect light, such as the planets, are made up from the third element. Moreover, it is the laws of motion that underpin and explain the laws of refraction and reflection of light, and the accounts of phenomena such as the rainbow and parhelia that are based on these. Setting out twelve ‘principal’ properties of light which a theory of light must account for he proceeds to show that his account is not only compatible with all of these, but can actually explain them. The work ends abruptly with an unfinished chapter 15.

The text was published posthumously by Descartes’ pupil Claude Clerselier (1614-1684) who added, anonymously, Descartes’ brief treatise Discours prononcé dans l’assemblée de Monsieur de Montmor, touchant le mouvement et le repos (pp. 31), and a Discours de la fiévre (pp. 30) whose author we have been unable to identify. The license for the work was given to Jacques le Gras, who made over part of the edition to Michel Bobin, Nicolas le Gras and Theodore Girard. Tchemerzine distinguishes three title pages: a, with the imprint of Theodore Girard; b, as in the present copy; and c, with the imprint of Jacques le Gras. No priority between these three issues has been definitively established.

Tchemerzine II, p. 801 (a); Guibert pp. 209-213; Honeyman 867 (issue a); NLM/Krivatsy 3133; Norman 629 (issue a). Clarke, Descartes, 2006.

8vo (159 x 101 mm), pp. [xvi], 260, 31, 30. Contemporary mottled calf (spine ends and corners worn, arms on covers with gilt worn away).

Item #5879

Price: $5,000.00

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