Galileo's life and works, like Gaul, has generally been divided into three parts. There is his work on mechanics and local motion (with the science of the strength of bodies grudgingly admitted), his work on astronomy and Copernicanism, and, finally, his relations and tribulations with the Catholic Church. Occasionally, some scholars under the anachronistic rubric of methodology have attempted to tie the two scientific parts together to obtain a more coherent picture.

In the space of this essay, I cannot overcome this tripartite division that the centuries have sanctioned. I can, however, sketch a picture of Galileo that will be a step toward this goal. It seems to me that Galileo had only a few basic conceptions that directed his life and work in all these three areas. His first belief concerned the role of the properly thinking and working individual scientist as being able to obtain knowledge and certainty. This belief showed up in his writings about the role of the scientific elite individual, who saw and understood things that were not seen by the masses, or, especially, by groups dedicated to the authority of Aristotle. It also seems to lie at the heart of his thoughts about Biblical exegesis. This individualism is apparent in Galileo's texts by his ubiquitous and consistent use of the first person singular "I" ("io") and the use of proper names or descriptions to talk about insights, discoveries, and all the accomplishments of good science.