Descartes

In 1633 Rene Descartes, philosopher and geometer, then thirty-seven years old, was preparing for publication a great work, Le Monde et le Traite de l’Homme, when at the end of November of that year the news arrived at Deventer, Holland where Descartes was staying at that time, of the persecution to which Galileo had been subjected in Rome. Not desirous of coming into conflict with the Catholic Church, Descartes decided against the publication of his work and, being also a practicing Catholic, he wrote to the mathematician Marin Mersenne:

This [the condemnation of Galileo] came as so much of a surprise to me that I have all but made up my mind to burn my papers in their entirety, or at least not allow them to be seen by anyone. For I could not imagine that Galileo would have been prosecuted for anything else but that, no doubt, he must have wanted to establish the motion of the Earth which, I am well aware, was at one time censured by several cardinals; but I thought I heard it said that even afterwards the public teaching of it was not discontinued, not even in Rome; and I confess that if it is wrong, so are the entire foundations of my philosophy, for it [i.e., the motion of the Earth] is demonstrated by them, evidently. And it is so closely tied to all parts of my treatise that I would not know how to separate it without making the rest defective. But since I would not for anything in the world want that from me should come so much as a word disapproved of by the Church, I would prefer to suppress it, rather than to let it appear mangled. . . . I beg you also to send me whatever you know about the Galileo affair.

Descartes never again picked up the manuscript, and it was not published until decades later, long after his death. Instead, in 1644, Descartes published his Principes de la Philosophie, in which he developed his theory of the mechanism of planetary motions. The universe is filled with subtle matter, some kind of effluvium, not much different from the ether of later authors; the sun by its rotation causes this effluvium to be concentrated in vortices that carry the planets around the sun on their orbits.

Whatever was the manner whereby matter was first set in motion, the vortices into which it is divided must now be so disposed that each turns in the direction in which it is easiest for it to continue its movement for, in accordance with the laws of nature, a moving body is easily deflected by meeting another body.

Descartes’ theory of vortices soon became the accepted teaching about the mechanism of the solar system.

Descartes himself proved, however, that philosophers who solve the mysteries of the world can commit fatal mistakes. After some deliberation and wavering, he accepted the insistent invitations to teach philosophy to Queen Christina of Sweden. As so many shallow persons, she was flattered to have the most famous philosopher of Europe at her feet—and actually at her bedside—for she ordered him to appear every morning at five to start the lesson. He cared for nothing more in his habits as for a late rising. The cold nights and early morning hours in the winter of Sweden broke his health, and four months after arrival in Sweden he died there from pneumonia.