Descartes: A Biography

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 Descartes: A Biography

to Professor Roberval, Descartes ‘made absurd objections against it in his

first writing, to which we replied in keeping with our understanding of the

same method, [and] he replied in such a way that he got entangled in other

objections which are as absurd or more so than the first ones’ (ii.).

When Roberval sent a discussion of the cycloid to Mersenne, Descartes

in turn scoffed at the significance of the discovery. ‘I do not see that he

has any reason to boast so much about finding something that is so simple

that anyone who knows the least amount of geometry could not fail to find

it simply by looking for it’ (ii.).

There was no sign of a resolution of these mathematical disputes in.

In fact, Descartes seems to have been preparing himself for a lengthy duel

byitemizing, in a letter to Mydorge (March), all the letters and writ-

ings exchanged by both sides.There were promising signs of a thaw and

of a suppressed magnanimity on Descartes’ part, when he discovered that

Fermathad not received his earlier replies (because, as usual, Mersenne

had failed to forward them), and that the Toulouse mathematician had

been offended by the vigour of Descartes’ reply.

As regard the fact that he [Fermat] says he found sharper words in my first reply than

he would have expected, I ask him very humbly to forgive me and to believe that I did

not know him. HisDe maximisarrived as a challenge from someone who had already

tried to refute myDioptricseven before it was published – as if to choke it before its

birth – by getting a copy of it that I had not sent to France for that purpose....Those

who disguise themselves at the carnival are not offended if people laugh at the mask

they wear and if they do not salute them when they pass them on the street, as

they would if they were dressed in their normal clothes. Likewise, it seems to me,

oneshould not object if I replied to his writing completely differently than I would

have replied to him in person, as someone whom I esteem and honour as his merit

requires. (ii.)

This apparent change of mind merely illustrates the frequent oscillations

in Descartes’ attitude to Fermat. In the same letter as that just quoted, he

suggested that Fermat’s actions confirmed completely what he [Descartes]

had suspected from the beginning, ‘that Fermat and those in Paris had

conspired together to try to discredit my writings as much as possible’

(ii.).

The following month Descartes wrote to Fermat in phrases that seemed

once again to augur a cessation of hostilities.

I was no less happy to receive the letter in which you do me the favour of promising me

your friendship than if it had come from a mistress whose favours I had passionately