This chapter investigates the practice of employing epigraphs in eighteenth-century natural history books. It examines, quantitatively and qualitatively, the significance of these very special parts of text, which are elements of both paratext and intertextuality, and which are very widespread in every kind of literature during the Enlightenment. We aim to describe their origin, their role in the architecture and the organization of the book, as well as the ways they establish connections with other works. We attempt to understand their various functions and, in that respect, the differences between the uses of epigraphs in several European languages are considered. We argue that besides their aesthetic role, epigraphs were often endowed with a diversity of other functions by authors as well as publishers and readers, in connection with the content of the book, the other elements of the paratext (title, front illustrations, etc.) and the context. Accordingly, epigraphs make sense, for example, of the aims of the authors, the patronage networks, and the intended targeted and real audience of scientific works.