In this paper I focus on John Locke as a representative figure of English Enlightenment theorizing about the legitimacy of cognitive authority and examine the way in which a greater attention to the cultural milieu in which Locke worked can lead to a profound reexamination of his writings on cognitive authority. In particular, I suggest that an inattention to the rise of a culture of reading and the growing availability of books in Early Modern England has led historians of philosophy (...) largely to misrepresent Locke's theory of testimonial justification. At the core of my paper are two interrelated claims. First, with respect to the history of ideas, I argue that the Locke's interest in testimony as a source of justification was in fact greater than that of his Scholastic forebears, and that this fact has a simple, if as yet unacknowledged, cultural cause -- viz., the rise of the book as a mass commodity in the late 17th century. Second, with respect to the history of philosophy more particularly, I argue that this failure to acknowledge the cultural movements that led to a consideration of testimony as a topic of interest to epistemologists in the Modern era has led to a misreading of Locke's work on the subject. Indeed, Locke, though usually read as having attempted to denigrate testimony as a legitimate source of justification, in fact sought to devise an epistemology that would do justice to the centrality of testimony in the intellectual lives of growing numbers of his contemporaries in 17th and 18th century England and Scotland. (shrink)