Building on the analysis of material production and science in Chap. 1 , this chapter deepens the investigation of the historical preconditions for the rise of modern natural science. Lefèvre explores how the objective idealist worldview of feudal society—rooted in the social structure of land-based, autarkic production—gradually gave way to a materialist conception of nature, grounded in the emerging bourgeois mode of production. He traces the dialectic between forms of labor, social relations, and conceptions of nature across key historical junctures, emphasizing the transition from speculative to scientific thought. The chapter focuses particularly on astronomy—from Copernicus to Galileo and Kepler—as a case study for understanding how a new scientific worldview could emerge only when the social and material foundations allowed nature to be grasped as a self-regulating, law-governed totality. Lefèvre concludes that the development of modern science was not technically necessitated by production needs but ideologically required by the bourgeois struggle against feudalism.