 Descartes’s speculations conveyed to his successors at least two issues relevant to the origin and history of living species. First, by presenting the historical account of the origin of the solar system and the world as a counterfactual hypothesis, a means of understanding the history of nature that was adapted to the limitations of the human mind, rather than as a literally true account, Descartes provided the option of a purely fictionalist reading of historical science that persisted into the nineteenth century (Sloan 2006a). Second, the integration of living beings into the new natural philosophy of mechanistic naturalism was left unresolved. If anything, Descartes’s reflections accentuated the problem of providing a naturalistic explanation of the origins of living beings.