 The reader may find this claim confusing, however, because in the just-preceding paragraphs Kuhn had emphasized the ontological and conceptual changes of precisely this revolution, e.g., the radical change in the concept of mass. Einstein’s masses are not Newtonian masses, he insisted. They are newly introduced entities; hence, we may infer, new content. Yet Kuhn surely does have a point worth saving, in that relativity theory still deals with most of the same kinds of phenomena and problems as classical mechanics and employs immediate successors to the classical concepts. But, if so, then reorganization of familiar materials implies a disciplinary continuity through revolution that Kuhn minimized.