On 28 July 1634 Marin Mersenne wrote to Nicolas-Claude Fabri de Peiresc; the opening lines of his letter contain this request:Je vous envoye les trois petitz traitez que j'ay faits, affin que vous en puissiez recevoir quelque contentement parmi vos occupations plus serieuses.Je vous prie d'envoyer a Mr Doni,1 quand vous en trouverez l'occasion, ceux ou son nom est. Dont les Questions morales, mathematiques, etc. sont differentes des vostres, parce qu'il y a des raisons pour le mouvement de la Terre sans refutation, pour lesquelles j'avois mis la sentence des Cardinaux pour medecine, comme vous verrez. Mais parce qu'on me dist qu'il y avoit eu quelque bruit parmi les docteurs de Sorbonne a cause des raisons que je ne refutois pas, j'ay oste toutes les questions dont ils se pouvoient formaliser, et en ay mis d'autres que vous verrez dans le livre pour Mr Doni, qui sera plus propre pour Rome.2[I am sending you the three small Treatises which I have composed, so that you can get some pleasure from them in the middle of your more serious projects.When you get the chance, I would like you to send to Mr Doni those in which his name appears. Among them the Questions morales, mathematiques, etc, are different from your copy, because yours contain reasons for the movement of the Earth which have not been refuted; as you can see, when I discuss those reasons, I have taken as my yardstick the judgement of the Cardinals. But because I was told that some Doctors of the Sorbonne had been unhappy that I had not refuted some of the reasons for the movement of the Earth, I have expunged all the material to which they might have objected, and in its place have put other questions which you will see in the book for Mr Doni, which will be more suitable for Rome.]The Faculty of Theology (the Sorbonne) had given its approval for Henri Guenon to print Les Questions theologiques, physiques, morales et mathema-tiques on 20 June 1634: the Privilege du Roi is dated August 1634. So, despite Mersenne's anxiety that some Doctors in the Sorbonne had misgivings about some of its content, there appears to have been nothing out of the ordinary about its publication.3 It is a work of truly baroque eclecticism; a huge range of physical, geometrical and musical questions are discussed, including (and purely by way of example) the speed of falling bodies (Question IV), the best way of finding longitude at sea (Question XII), the quadrature of the circle (Question XVI), the qualities of light (Question XXI), the transparency of crystal (Question XXIV), the respective qualities of heat and cold (Question XXV), magnetism (Question XXVII), sunspots (Question XXIX).4 What lends the work its abiding interest, though, are the reasons why Mersenne judged it prudent to substitute innocuous material for some of the Questions which dealt with current astronomical problems, and why an expurgated version should have been considered 'more suitable for Rome' than the original. It is the argument of this article that the answers lie in the events which took place in Rome the previous year, and, in a more general sense, in the reactions of French savants to the condemnation of Galileo,5 and to the injunction against reading his works.Marin Mersenne (1588-1648) 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. 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 le 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. …