Newton on Matter and Activity shows persuasively that while the Principia remains within the first two stages of inquiry (mathematical and physical) into nature, Newton spent the next forty years of his life making a philosophical analysis of matter, force, and transmission of force. Close attention is paid to methodological issues, especially Newton's move beyond inductivism and toward a reproductive theoretical schema of interpretation required to treat of attraction, hardness, and impenetrability. --Cross Currents