During the eighteenth century, the specter of atheism was a major concern among many intellectuals in Europe. Many of the leading figures of the period such as François-Marie Arouet de Voltaire refuted atheism at every turn. These debates centered on living organisms, particularly questions about generation. Efforts to explain the process of generation raised biological, religious, and political questions. One popular theory put forward to address the question of generation was preformation, the belief that “germs” had been in existence since (...) God created the world. This chapter first discusses the rise of preformationist thinking in the late seventeenth century before turning to the biological evidence that challenged preexistence in the mid-eighteenth century and analyzing the reaction it triggered among the preformationists. It also examines the work of Voltaire and Denis Diderot to illustrate how the generation debates are linked to the materialism question. The chapter concludes by showing how these controversies about nature and biology became entangled with politics in eighteenth-century France. (shrink)