For a philosopher with an abiding interest in the nature of objective knowledge systems in science, what could be more important than trying to think in terms of those very subjects of such knowledge to which men like Galileo, Newton, Max Planck, Einstein and others devoted their entire lifetimes? In certain respects, these systems and their structures may not be beyond the grasp of a linguistic conception of science, and scientific change, which men of science and philosophy have advocated in various forms in recent times. But certainly it is wrong-headed to think that one's conception of science can be based on an identification of its