Many have difficulties understanding what Kuhn meant when he spoke of “world change” due to revolutions. I reconstruct the historical path in which the idea emerged that reality is not something purely object-sided. The path starts with Copernicus’ new planetary system. The motions of the Sun and the planets, previously seen as purely object-sided, were now seen as containing genetically subject-sided contributions. A similar process, also at the center of the constitution of modern science, was the introduction of secondary qualities in the seventeenth century. In these historical processes, the reality status of something, whose reality seemed beyond doubt, changed dramatically. Philosophical reflection of such processes culminates in Kant’s critical philosophy. Ever since, this kind of “post-Copernican thinking” has been an indispensable part of the Western intellectual tradition, and it surfaced in the development of special relativity and quantum mechanics. I argue that Kuhn is continuing this tradition. Understanding this genealogy may make Kuhn’s metaphysics accessible to those realists who maintain that talk of genetically subject-sided contributions to reality is utterly inconsistent.