To the present day, clinical teaching has not been the most important means of transmitting psychiatric knowledge. In different stages of professional training, knowledge is mainly conveyed and shaped through textbooks—students and teachers read and reread books in order to gain or dispute insights within a vast and complex medical field. This project investigated the culture of the psychiatric textbook as a crucial aspect in the formation of the discipline. It reconstructed the writing, reading, and teaching practices by focusing on the rhetoric of the book, its strategies of visualization, narrations, and typographic codes. Particular emphasis was placed on the late nineteenth and early twentieth century, when psychiatry entered into its phase of professionalization. How did textbooks contribute to this process? And how—if at all—did they lead to the formation of “a collective thought style,” as Ludwik Fleck suggested?