The article critically explores the different paths chosen by closely related historical disciplines: intellectual history and the history of books. While the former has focused on discourse analysis, the latter has given more attention to the study of diffusion. Historians who study the diffusion of books commonly run into a difficulty: the best-sellers of the past may serve as an indicator of public taste, but they may also be trivial, and they do not necessarily lead to explanations of important events such as the Reformation and the French Revolution. On the other hand, discourse analysis is confined to a narrow band of textual evidence, and thus cannot provide much insight on the values and views of ordinary people caught up in the patterns of everyday life. The author concludes by discussing how the history of books, particularly the history of reading and the history of publishing, can have important implications for the study of discourse.