John Locke's comparison of the mind to a blank piece of paper, the tabula rasa, was one of the most recognizable metaphors of the British Enlightenment. Though scholars embrace its impact on the arts, humanities, natural sciences, and social sciences, they seldom consider why the metaphor was so successful. Concentrating on the notebooks made and used by the schoolchildren of Enlightenment Scotland, this essay contends that the answer lies in the material and visual conditions that gave rise to the metaphor's usage. By the time students had finished school, they had learned to conceptualize the pages, the script, and the figures of their notebooks as indispensable learning tools that could be manipulated by scores of adaptable folding, writing, and drawing techniques. In this article, I reveal that historicizing the epistemology and manipulability of student manuscript culture makes it possible to see that the success of Locke's metaphor was founded on its appeal to everyday note-keeping activities performed by British schoolchildren.