Galileo

Galileo's contribution to present scientific thinking was threefold: (1) he was the first to appreciate the value of experiment and might well be called the father of experimental physics; (2) he was able to imagine an ideal situation, such as a frictionless medium, and thereby to explain discrepancies between actual and theoretical results; and (3) he recognized the value of mathematical analysis in the study of physical principles. - p. 7.