Mersenne as Translator and Interpreter of the Works of Galileo

At the height of his reputation, Marin Mersenne (1588-1648) sent Galileo three complimentary letters: all three went unanswered (or at least no replies are extant). When Galileo wrote to his Swiss colleague and supporter Elia Diodati, he excused himself for not replying to Mersenne with the rather limp excuse that he found Mersenne's handwriting too hard to read.¹ It was not the first time that Galileo had ignored French scientists who wished to consult him, or simply wished to expressed their admiration for his work.² Galileo's rather patronizing attitude towards Mersenne belies the way in which posterity has defined their relationship, as one based on warm admiration, constant support and helpful intercession,³ which took a great deal of time to mature; even then, one might question whether that relationship was truly bilateral,⁴ and more importantly, whether Mersenne's science was expressed with different emphases.⁵ The central tenet of this article is that their relationship was far more complex than traditionally accepted, and needs to be re-assessed. As we shall see, Mersenne never espoused Copernicanism unreservedly, and it was always Galileo's views on the applied sciences of mechanics and dynamics that attracted him, probably because his own interests lay in those spheres of investigation. Yet it was, of course, the astronomical question that dominated scientific debate, particularly after Galileo's initial interview with Cardinal Roberto Bellarmine, and the injunction placed upon him in 1616. In the specific context of Mersenne's views, and since Mersenne's influence with the European scientific community was so widespread,

his attitude toward Copernicanism helped create a climate of opinion, not only in France but throughout Europe generally. His reaction is of particular interest, therefore, in attempting to assess the impact on Catholic science of the Church's intervention in the astronomical controversy.⁶

Pierre Boutroux's early attempt to trace Mersenne's attitude to heliocentricity saw in him an "adversaire résolu du système de Copernic," a Catholic priest obedient to the decree of 1616,⁷ even though Mersenne was at that time completely unfamiliar with Galileo's writings; but that by the following year he had assumed that Mersenne had completely altered his view.⁸ Hine gives a more thoroughly researched and more convincing portrait of Mersenne as a questioning Catholic scientist for whom none of the competing astronomical systems offers enough proof to convince him.⁹ While the astronomical question would come to dominate Galileo's relationship with Mersenne, it lay very much ahead of Mersenne's initial interest in Galileo's work.

Marin Mersenne was a Minim priest who played a crucial role in the transmission of intellectual ideas in seventeenth-century France, diffusing new theories on all of the natural sciences, music, literature and the arts through a large and influential network of correspondents.¹⁰ That network was not limited to France, but stretched from Scotland to Tunisia, and from England to Egypt. He was particularly instrumental in spreading news of the astronomical discoveries of Galileo, and in keeping his correspondents aware of events in Rome surrounding his trial and condemnation in 1633, in the wake of the publication of the Dialogo sopra i due massime sistemi del mondo. It was often said of Mersenne that to inform him of a discovery meant to publish it throughout the whole of Europe. His Couvent de l'Annonciade near the Place Royale (now the Place des Vosges) in Paris became the meeting place for scientists of the caliber of Fermat, Gassendi, Roberval and Beaugrand. It was here, for example, that the young Blaise Pascal took his first steps in scientific society. As influential as these embryonic salons were for the exchange of books, and for general cultural exchange, Mersenne's career, more than that of any other savant, illustrates the contemporary importance of written correspondence; one might go so far as to say that as the Epistolier des frères minimes, a large part of Mersenne's day-to-day life was taken up with writing letters. Most savants of...