This paper examines the points of disagreement between Petrus Camper and J. W. von Goethe regarding the existence of the inter-maxillary bone in humans as the link between man and the rest of nature. This historical case illustrates the fundamental role of aesthetic judgements in scientific discovery. Thus, I shall show how the eighteenth century discovery of the inter-maxillary bone in humans was largely determined by aesthetic factors—specifically, those sets of assumptions and criteria implied in the aesthetic schemata of Camper (...) and Goethe. I argue that the relevance of scientifically ascertainable morphological properties that count as evidence for the existence of bona fide anatomical structures depend on the aesthetic schema adopted by the communities assessing the classification. At the same time, I propose and explain mechanisms by which aesthetic considerations might determine the acceptability of empirical claims about the world. Based on the reconstruction of the arguments of Camper and Goethe, I conclude that aesthetic considerations play a substantive role in both the generation and preliminary evaluation of scientific hypotheses. This paper suggests a complementary relation between the mediation of aesthetic criteria in theory choice and in scientific discovery in that while aesthetic considerations in theory choice lead to conservatism; in the context of discovery they often lead to innovation. (shrink)