Fleck's social theory of science refers to many ethnological examples in order to explain how collective thinking and acting constructs certain systems of belief and knowing. According to Fleck, scientific concepts and practices are comparable with magic terms and ceremonies. This essay aims to identify the ethnological sources that Fleck's epistemology is using. By confronting them with other relativistic theories that were circulating in Lemberg during the interwar period, the originality of Fleck's own position can be contextualized and explained as well.