Arguing about the stars has rarely been more controversial and dangerous than in the early modern period in Europe, especially in Catholic countries, in a time when old and novel conceptions of the heavens, planetary models and theories of celestial motions and influences were intensely debated, revised and scrutinized for philosophical soundness and religious conformity. In the hundred years or so that witnessed the birth and censorship of the Copernican theory; the execution in Rome of the most passionate defender of post-Copernican cosmology, Giordano Bruno (1548-1600), and the rise and fall of Galileo Galilei's (1564-1642) fame linked to his novel interpretation of the book of nature, the Catholic Church created some of the most powerful instruments of cultural control and educational conformity ever seen: the Inquisition, the Index of Forbidden Books and the vast network of Jesuit schools that spread from Rome and the Iberian peninsula across the globe.