While some early-modern philosophers had brushed with the problem of verbal equivocity, Locke makes it a central plank in his critique of language. It was a deeply embedded assumption that men share the same mental discourse. Think, for example, of the universal language projects, and in particular of the frontispiece of Cave Beck's Universal Character, where an Englishman (is it Bacon, the father of the movement?), a Turk, a grass-skirted American and a figure who is harder to decipher (is it an African, or a Roman in the shadows of time?) all communicate with each other at the table. Think also of the generic mind of the trivium, the rationalising, ‘philosophical’ grammarians and the worldwide res. Reacting against this commonplace and drawing on its detractors, Locke goes so far as to say that semantic instability is endemic to language. His predecessors had probed the phenomenon, particularly in the contexts of the elocutionary use of language, superficial semantic disagreement in the self-consciously conciliatory republic of letters, textual hermeneutics, hedonistic moral terminology and mental divergence. While Locke repeats and develops these themes, he also takes the radical step of identifying the problem as one that affects language per se. It is part and parcel of the human condition. If we talk at cross purposes then we cannot understand one another, and language as a whole becomes a bankrupt enterprise.