The role of language in development has been a central theme in post-war English. However, the European history of ideas about the role of signs has been insufficiently appreciated. I aim to enrich readings of contemporary urban classrooms by recovering something of this history. As the culmination of this work, I trace the story of a poem, written by a Black student in a London classroom, back into the history of discussions and debates that a class conducted with itself over five years. From perspectives provided by the history of ideas and recent work in social memory, I show how the student's representation of a childhood recollection (a visit to the site of a former plantation) was mediated and shaped by 'pedagogical artefacts'. I give a history of one such artefact as an instance of the role of signs in a contemporary classroom. A picture of language as human invention was drawn in the first instance during the European Enlightenment. From this picture a seminal theory about the role of signs in the mastery of mental operations emerged. On this view, memory and imagination depend upon signs. In the aftermath to the French Revolution, language was linked to conceptions of citizenship and human advancement. In Germany, the picture of language was redrawn in the light of Kant's epistemology, and connected to an educational ideal of selfcultivation. In the nineteenth century, 'cultural' psychology attempted unsuccessfully to combine a notion of signs in the development of higher mental functions with findings in experimental psychology. Subsequently, the introduction of a distinction between mental 'contents' and mental 'acts' fostered new research into the role of signs in consciousness. Concurrently, an ethical vision of symbolisation as the 'common ground' of humanity issued from a philosophy of symbolic forms. As a whole the thesis seeks to show the continuing relevance of this history.