Descartes: A Biography

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mani`ere tr`es-imparfaite, sous le titredu Monde ou Trait ́edelaLumi`ere.’ Baillet

(), ii..

.This was first published in a Latin translation prepared by F. Schuyl, asDe Homine

(Leiden,). The French text was edited by Clerselier, with notes prepared by

Louis de la Forge, and it was published together withUn Trait ́edelaFormation

du Foetusin.

.Galileo is usually credited for having been the first to raise this question, inThe

Assayer(). The possible disparity between appearance and reality in our sen-

sations subsequently became a famous philosophical problem, under the title of

primary and secondary qualities, for seventeenth-century authors such as Robert

Boyle and John Locke. For Galileo’s discussion, see Galilei (),–.

.Quintilian (), V, x..

.Moliere (` ), ii..

.The extent to which animal spirits in motion were expected to explain all animal

motions is clear from the following: ‘You will have no difficulty in concluding from

the foregoing that the animal spirits are able to cause movements in all bodily parts

in which the nerves terminate, even though anatomists have failed to find any that

are visible in parts such as the eye, the heart, the liver, the gall bladder, the spleen,

and so on’ (xi.). The fact that these nerve connections were invisible to the

naked eye and had not yet been observed by anatomists (because the microscope

had not yet been invented) did not deflect Descartes from his claim. He was

proposing a model or hypothesis about how such movements could occur, and

the failure of anatomists to see the corresponding ducts did not count against the

explanation.

.Forexample, he writes about God uniting ‘a rational soul to this machine’ (xi.,

,), and he concludes theTreatisewith a sentence to introduce the second

part, ‘the description of the rational soul’ (xi.). Evidently, this part was never

written or, at least, has not survived. Descartes also leaves room for a ‘soul’ at

critical points in his discussion of sensation (xi.,).

Chapter

.Descartes encountered serious objections later to the metaphysical discussions

that were outlined in Part IV of theDiscourse on Method, and he may have been

protecting himself from the ire of theological critics by publishing his book anony-

mously.

.He had acknowledged this in a letter to Mersenne, April: ‘all the things that I

explain in my treatise, among which was also the view about the earth’s movement,

are so interrelated that it is enough to know that one of them is false to conclude

that all the reasons that I used are unconvincing; and although I thought that they

were supported by very certain and very evident demonstrations...’ (i.).

.Descartes to Mersenne,May(i.).

.Beeckman (–), iii.,,.

.Morin ().