This paper analyses the contents and the style of the Bullettino di bibliografia e di storia delle scienze matematiche e fisiche (1868–1887), the first journal entirely devoted to the history of mathematics. It is argued that its innovative and controversial methodological approach cannot be properly understood without considering the cultural conditions in which the journal was conceived and realized. The style of the Bullettino was far from being the mere outcome of the eccentric personality of its editor, Prince Baldassarre Boncompagni. Rather, it reflected in many ways, at the level of historiography of science, the struggle of the official Roman Catholic culture against the growing secularization of knowledge and society.