Chapter 13: This chapter traces the theatrum mundi (theatre as world) metaphor back to its technical and philosophical roots. By comparing iconographic sources from scientific texts with scenographic ones, the chapter follows the evolution of the notions of machine and wonder in the seventeenth century and argues that the material culture of theatre played an important role in the development of Cartesian physics and the new cosmology and, in particular, in the mechanization of the world picture. The chapter focuses on the relationship between Fontenelle, Descartes, and the engineer and architect Giacomo Torelli, whose scenography gained him the name of ‘the great sorcerer’. Paradoxically, it is by taking up Torelli’s design, combined with Descartes’s new definition of meteors, that Fontenelle manages to define a new type of ‘wonder’, scientific and no longer magical.