In the past few decades historians have become increasingly concerned with the role played by language in our understanding of social and political life. The theoretical sources for this concern are several and not infrequently contradictory. But if the works of Wittgenstein, Heidegger, Austin, Ryle, Foucault, Derrida and Rorty (to take only a random sample) often have little else in common, they have all, in different ways and with different ends in view, insisted upon the interdependence of the propositional content of an argument and the language, the discourse, in which it is made. At the most fundamental level such languages will be composed of precise vocabularies, metaphors and topoi, even recognised authorities, all readily identifiable and easily transmitted from one author to another. But there are also other levels, less easy to identify, at which it makes sense to say that a particular author is speaking in the language of, say ‘humanism’ or ‘scholasticism’ or ‘political economy’. Such languages are, as J. G. A. Pocock says here, ‘distinguishable language-games of which each may have its own vocabulary, rules, preconditions and implications, tone and style’ which the historian has to learn to ‘read’. They are, to borrow a term from Hobbes, ‘registers’ in which specific kinds of propositions may intelligibly be cast.