Bruno had returned in October 1585 to Paris, where he has found a changed political atmosphere.

Henry III has abrogated the edict of pacification with the Protestants, and the King of Navarre has been excommunicated.

Far from adopting a cautious line of behavior, however, Bruno enters into a polemic with a protégé of the Catholic party, the mathematician Fabrizio Mordente, whom he ridicules in four Dialogi, and in May 1586 he dares to attack Aristotle publicly in his Centum et viginti articuli de natura et mundo adversus Peripateticos (“One hundred and twenty Articles on Nature and the World Against the Peripatetics”).

The Politiques disavow him, and Bruno leaves Paris for Germany.