The correct answer is: "the scientific method".
Galileo Galilei (1564 - 1642) was an Italian astronomer, physicist and engineer, known as the "father of observational astronomy" and "of the scientific method".
He conducted research on speed and velocity, gravity and free fall, the principle of relativity, etc. Through observational methods, he was able to describe the properties of such phenomena and to develop "laws" as a starting point for human understanding of them. He confronted the Roman Inquisition by defending the heliocentrism theory developed by Copernicus.