Language was a problem for early-modern philosophers. Not only were a remarkable number of works devoted to the subject, but it intruded upon texts about nature, morality and politics. At a time when both the portrayal of reality and our access to that reality were being challenged, and when religious and political conflicts proliferated, language came to seem dangerously unhinged. It was supposed to reach out to the world and to mediate between men, but instead it barred the way. As perceptions of the natural and cultural worlds mutated and splintered, it was feared that language no longer mapped them. Yet language was not silent. Covering over the cracks in the semantic edifice, it told its own duplicitous story. It seemed to have a power of its own. Unfettered in practice by the forces that ought to have constrained it, it tore at knowledge and at the community. So pressing was the unease about language that when John Locke came to write his great work on human understanding, he felt impelled to include an entire book on words. This inclusion is even more surprising when one considers that the Essay concerning Human Understanding (1689) is recognisably a work of logic. Logics old and new had, in the main, treated ideas and words simultaneously, and even interchangeably, explaining how these simple units were gradually compounded by the mind in a process that culminated in chains of reasoning.