Galileo’s Idol is a historical case-study of the use of information in the making of early modern scientific knowledge. It studies the relationship between natural philosophical and political practices in the Venetian Mediterranean at the start of the seventeenth-century. Using the figure of Galileo’s closest friend and confidant, Gianfrancesco Sagredo (1571~1620), it shows how techniques of political information exchange were appropriated by early practitioners of the new science. Practices such as intercepting, leaking and archiving documents were used to redirect information towards varied audiences who read, understood and used this information in newly productive ways. Sagredo’s hybrid interventions in both political and natural philosophical debates are described for the first time, within the interlocking contexts of Venetian conflicts with Rome, the jostle of Mediterranean colonialism and the broken networks of Early Modern geopolitics. Special attention is paid to anonymous and pseudonymous texts, published both scribally and in print. A range of historiographical methodologies are deployed to locate and interpret evidence for this book, from extensive archival research, to detailed bibliographical analysis, to traditional art and new material history. What emerges in this microhistorical study is a refreshing corrective to the prevalent image of sombre, virtuous and autonomous natural philosophy: instead we see a satirical, carnivalesque science deeply enmeshed in political subterfuges and machinations, whose geopolitical interests extended well beyond the closed confines of Europe and intervened across the early modern world.