Descartes: A Biography

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 Descartes: A Biography

reason to believe in an indefinitely large universe or in a plurality of worlds

(both of which were Cartesian hypotheses).

There are intermittent references to progress on thePrinciplesbetween

and. Descartes acknowledges a request from Charles Cavendish

about grinding lenses as an implicit compliment on his own work and

an encouragement to publish what he calls ‘my Physics’.He sum-

marizes his explanation of magnetism, which postulated imperceptible

particles that pass through the Earth from the North and South Poles,

in both directions, and re-enter the Earth at the complementary pole.

Again, this is something he promised to explain more fully in what he

called ‘my Physics’.Descartes briefly consulted a new book on mag-

netism by the Jesuit Athanasius Kircher (–), but found noth-

ing significant in it either.By September,hewas able to tell

Huygens that Van Schooten’s son, who had drawn the diagrams for

hisDioptrics, was about to prepare the diagrams for ‘my Philosophy’,

and that the printer had promised to have all the work completed by

Easter.

During the final months of preparation, Descartes further reduced the

scope of thePrinciplesbyomitting two parts that were intended to discuss

animals and human beings. Pollot and Huygens evidently heard about the

change of plans, and this prompted Huygens to write, in October,

that he had heard that Descartes was withholding part of his ‘Physics’.

By the following month, he was pleading with the author not to ruin the

book by omitting the section on human beings. ‘Mr Pollot and I would

strongly advise that, in publishing your Physics, you should not mutilate

it of the part on human nature, and that you anticipate the likelihood that

what you conceal will always provide material for slander, as has happened

to you uptonow.’Descartes did not follow this advice for reasons that,

onthis occasion, seemed plausible. The author was very distracted by the

ongoing controversy at Utrecht, and he had not made enough progress

in his study of animals and human nature to include those sections in the

text. He explains the revised project in those terms in Part IV, Chapter

,ofthePrinciples.

Iwould not add anything else to this fourth part of thePrinciples of Philosophyif, as

I had previously intended, I were to write two other parts, the fifth part about living

things, animals and plants, and the sixth part about human nature. But since I have not

completely examined all the things that I want to write about there, nor do I know that

I will ever have enough time to do so, I shall add a few things here about the objects of