Adam Smith is often described as a member of ‘the Scottish historical school’ and as the author of a science of man that was framed and focused by a distinctive theory of history. But what sort of historian was he? Smith always thought of ‘history’ in conventional terms, as the study of political and military events, their causes and consequences. Like William Robertson, however, he believed that such an enterprise had philosophic potential. He thought that Tacitus had transformed the traditional scope of history by paying attention to ‘the temper and internall disposition of the severall actors who had shaped events’ and had shown that history was of value to ‘a science no less usefull, to wit, the knowledge of the motives by which men act.’ But although history studied in this Tacitean fashion could yield up information about the minds of statesmen and generals and the secret causes of particular policies, Smith was more interested in a history which explained the hidden causes of civilisation's progress from its barbarous to its polished states in terms of changes in the means of subsistence and the distribution of property. It was a move which heralded the appearance of that celebrated stadial theory of history which Dugald Stewart, somewhat opaquely described as ‘conjectural history’ and which remains one of the intellectual glories of the Scottish Enlightenment.