Proposes radical interpretations of key episodes of Galileo's career, including his telescopic discoveries of 1610, the dispute over sunspots, and the conflict with the Holy Office over the relationship between Copernicanism and Scripture. The book offers an account of the systems of exchanges, communication, and credibility at work in his career.

Galileo's tactics during this time shifted as rapidly as his circumstances, argues Mario Biagioli, and the pace of these changes forced him to respond swiftly to the opportunities and risks posed by unforeseen inventions, further discoveries, and the interventions of his opponents. Focusing on the aspects of Galileo's scientific life that extend beyond the framework of court culture and patronage, Biagioli offers a revisionist account of the different systems of exchanges, communication, and credibility at work in various phases of Galileo's career. "Galileo's Instruments of Credit" will find grateful readers among scholars of science studies, historical epistemology, visual studies, Galilean science, and late Renaissance astronomy.